JPH04279826A - Abnormality diagnostic method and device for adjustable speed rotating system - Google Patents

Abstract

PURPOSE:To enable the judgment of abnormality by means of vibration detection even in a rotating machine in which the number of revolutions fluctuates by converting the detected vibration signal of a rotating system into a pseudo vibration signal corresponding to that in the case of a standard rotational period, and by carrying out the frequency analysis and the autocorrelation analysis of this pseudo signal. CONSTITUTION:Vibration signals and rotational pulses are simultaneously taken by a vibration detector 2 and a pulse detector 4. The vibration signals processed by an envelope processing circuit 3 and the detected rotational pulses are stored in a memory 5. Further, a period-measuring means 6 measures the period between arbitrary pulses stored in the memory 5. On the other hand, a rotational period comparing means 7 calculates the ratio on the basis of the standard rotational period and the actual rotational period being input through a period-measuring means 6. The vibration signal in the memory 5 that has been subjected to time-interval change processing through a memory control means 8 is read out by an output circuit 9, and it is subjected to autocorrelation analysis processing by a judgment circuit 10, so that the calculation of period can be carried out even in the equipment of an adjustable speed rotating system 1, thus the location of an abnormal portion can be enabled.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention detects vibrations associated with abnormalities in rotating machines used in production sites, etc., especially in variable speed rotating systems where the rotational speed fluctuates. The present invention relates to a variable speed rotation system abnormality diagnosis method and apparatus for determining the cause of the abnormality.

0002

[Prior art] Early detection and detection of abnormalities occurring in rotating machinery, etc.
If repair is not performed, the abnormality will be amplified as it rotates, often resulting in a situation where repair is impossible.

[0003] Therefore, the vibrations of the rotating system that occur due to the abnormality are detected, and the abnormal location or the cause of the abnormality is determined based on the detected data.

[0004] The main methods of such determination include frequency analysis and autocorrelation analysis. The former method determines the content of the abnormality from the frequency spectrum of the vibration, and the latter method determines the content of the abnormality by examining the periodicity of the vibration signal.

Furthermore, in Japanese Patent Application Laid-Open No. 54-154059, the order ratio of the signal obtained by performing predetermined processing on the detected vibration signal and the rotational speed of a rotating machine detected by a rotational speed detector is disclosed. A method is disclosed in which an abnormality in the rotating machine is identified by inputting the data into an analysis circuit and determining the rotational order ratio.

[0006]

[Problems to be Solved by the Invention] However, in both the frequency analysis method and the autocorrelation analysis method described above, due to the characteristics of the analysis, the number of revolutions is kept constant or sampling is performed while changing the sampling period in proportion to the number of revolutions. A dedicated analog circuit was required to do this. If this is not done, there is a problem in that the diagnostic accuracy decreases in rotating machines where the rotational speed fluctuates.

The present invention was devised in view of the above-mentioned problems of the prior art, and it is possible to perform sampling without changing the sampling period even when the rotational speed changes, and to process the collected data. , to diagnose equipment whose rotational speed fluctuates.

[0008]

[Means for Solving the Problems] Therefore, the method for diagnosing an abnormality in a variable speed rotating system according to the present invention is to measure one or more of the displacement, velocity, and acceleration of vibrations generated in the rotating system by measuring the rotational speed of the rotating system. When the vibration acceleration is measured, the signal is passed through a high-pass filter to extract only the high-frequency components, and the measured vibration signals are rectified and subjected to envelope processing. The processed vibration signal and rotation period signal are sampled as digital signals at a certain sampling period, and the signals are sampled at the same time as the rotation period signal based on the ratio of the preset standard rotation period and the rotation period of the rotating system. The basic feature is that the time interval changing process of the vibration signal is performed, and then the abnormal site or cause of the abnormality is determined by frequency analysis or autocorrelation analysis of the vibration signal subjected to the time interval changing process.

The second invention relates to an apparatus for implementing the method of the first invention, and includes a vibration detector for detecting vibrations of a rotating system, and an envelope for rectifying and envelope processing a signal obtained from the vibration detector. A line processing circuit, a pulse detection means for detecting the rotation pulse of the rotation system one or more times per rotation, sampling the envelope-processed vibration signal and the detected rotation pulse, and detecting the rotation pulse in the paired area. A memory for storing each, a period measuring means for measuring the period between arbitrary rotation pulses stored in the memory, and a ratio between a preset standard rotation period and a rotation period measured by the period measuring means. a rotation period comparison means for converting the memory address of the memory where the vibration signal data is stored in pairs with the arbitrary rotation pulse whose period has been measured to a new address according to the above ratio, and converting the data in the memory. A memory management means that moves the data to a new memory address and changes the time interval of the data; an output circuit that reads out the vibration signal data of the memory after the movement for each rotation pulse; The present invention is characterized by comprising a determination circuit that determines the abnormality part or cause of the abnormality in the rotating system by frequency analysis or autocorrelation analysis of vibration signals.

[0010] The above data time interval changing process and the memory address conversion and memory data movement process performed by the memory management means to perform the process can be performed even if the rotational speed of the rotating system subject to vibration detection fluctuates. , which forms the basis of the configuration of the present invention that enables highly accurate diagnosis of abnormal conditions by frequency analysis and autocorrelation analysis.

Taking the operation of the memory management means of the second inventive device as an example, the operation will be explained as follows: A value obtained by multiplying a relative address starting from the first address of the original address of the memory by the above-mentioned cycle ratio and converting it into an integer. Determine the new memory address as the value of the relative address starting from the first address of the new address, store the data stored in the memory at the original address to the memory at the new address, and store the data in the memory at the new address. If no data has been moved from the memory at the original address, the same value as the data at the previous address will be stored, and on the other hand, data from different memory addresses at the original address will be stored at the same new memory address. If the data is stored earlier, the later data is overwritten and stored on top of the earlier stored data.

That is, the above signal processing is performed using a preset standard rotation period (this is a rotation period that is easy to determine by frequency analysis method or autocorrelation analysis method) for each rotation system. After calculating the percentage deviation from the ratio determined for each case, the vibration signal that has undergone the specified processing (signal processing required for frequency analysis method and autocorrelation analysis method) after detection is While minimizing distortion of the signal waveform, processing is performed to convert it into a pseudo vibration signal corresponding to the standard rotation period based on the above ratio, so even if the rotation speed is not stable, the frequency analysis method can be used. Highly accurate diagnosis using autocorrelation analysis and autocorrelation analysis methods becomes possible.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below together with an apparatus for implementing the method of the present invention (ie, a second apparatus of the invention) shown in FIG.

In FIG. 1, reference numeral 1 denotes a rotating system such as an electric motor whose rotational speed is varied by VVVF or the like, and its roll shaft 1a is supported by a bearing 1b. 2 is a vibration detector, and a vibration displacement-sensitive type, a speed-sensitive type, or an acceleration-sensitive type is applied.In particular, in the case of an acceleration-sensitive type that detects abnormalities based on acceleration, a 1KHz high-pass sensor is used. Only high-frequency region components of 1 KHz or more are extracted before being outputted to an envelope processing circuit 3, which will be described later, through a filter (not shown). This vibration detector 2 is attached to the bearing 1b of the rotation system 1. 3 is an envelope processing circuit which rectifies the vibration signal inputted from the vibration detector 2 and then performs envelope processing. Reference numeral 4 denotes a pulse detection means for detecting rotational pulses of the rotating system 1, which is attached in a non-contact manner to any location on the roll shaft 1a of the rotating system 1, and generates an electric signal of one pulse per rotation. Reference numeral 5 denotes a memory, which samples the envelope-processed vibration signal and the detected rotational pulse every 1 ms and stores them in paired areas, respectively. Reference numeral 6 denotes a period measuring means, which measures the period between arbitrary rotation pulses stored in the memory 5. 7 is a rotation period comparing means, which compares a standard rotation period preset to 100 ms (rotation speed 600 rpm);
The ratio (standard rotation period/actual rotation period) with the rotation period measured by the period measuring means 6 is calculated. Reference numeral 8 denotes a memory management means, and a memory 5 stores vibration signal data paired with an arbitrary rotation pulse whose period has been measured.
The memory address is converted to a new address based on the above ratio, and the data in the memory 5 is moved to the memory 5 at the new address, and the time interval of the data is changed. 9
is an output circuit, which reads data from the memory 5 that has been subjected to time interval changing processing. Reference numeral 10 denotes a determination circuit, which specifies an abnormal portion of the rotating system 1 by autocorrelation analysis (frequency analysis may also be performed) of the vibration signal based on the read data.

Next, a case will be described in which abnormality diagnosis of the variable speed rotation system 1 is performed using a diagnostic device having such a device configuration.

As shown in the flowchart of FIG. 2, vibration signals and rotation pulses are simultaneously collected by the vibration detector 2 and the pulse detection means 4. At this time, if the vibration detector 2 is of an acceleration-sensitive type and determines abnormalities in the acceleration signal, only high frequency components of 1 KHz or higher are extracted through a high-pass filter. Thereafter, the vibration signal is rectified by the envelope processing circuit 3, and then envelope processing is performed. The rotation pulses detected in the above manner are shown in Fig. 3 (
Pulse waveforms as shown in a), (b), and (c) are shown. The figure (a) shows when the rotation period of the rotating system 1 is 100 ms (rotational speed 600 rpm), and the figure (b) and (c) show the rotation period when the rotation period is 80 ms (750 rpm) and 120 ms (rotational speed 600 rpm).
0 rpm) are shown. on the other hand,
Assuming that the vibration signal processed by the envelope processing circuit 3 has five peak waves per rotation, the vibration signal is as shown in Fig. 4 (
The signal waveforms are as shown in a), (b), and (c). In addition, Fig. 4(a) shows the flaw period (20ms) obtained from the vibration signal generated when the rotating system 1 rotates at the standard rotation period as shown in Fig. 3(a), and Fig. 4(b) (c) is 80
The flaw periods (16 ms, 24 ms) obtained from vibration signals generated during rotation with periods of ms and 120 ms are shown.

The envelope-processed vibration signal and the detected rotational pulse are stored in the memory 5 in pairs every 1 ms.

Furthermore, the period measuring means 6 measures the period between arbitrary pulses stored in the memory 5 (in the embodiment, there is a fluctuation in the rotational speed of the rotating system 1, and the period is initially 100 ms).
(However, rotation periods of 80 ms and 120 ms were later measured.)

On the other hand, the rotation period comparing means 7 has a standard rotation period of 100 ms as shown in FIG. The ratio of (standard rotation period/actual rotation period) is calculated based on the actual rotation period. This ratio becomes the time interval change coefficient αi that determines the method of changing the memory address when the memory management means 8 performs the next time interval change process.

Next, the memory management means 8 performs a process corresponding to the time interval changing process that is performed after the envelope process shown in FIG. This is to change the allocation of memory addresses and move the memory data accordingly. This process is performed based on the time interval change coefficient αi calculated by the rotation period comparing means 7 described above based on an arbitrary rotation period (temporarily set as the i-th rotation period), and the period measurement is performed as shown on the left or right side of FIG. 1m paired with any rotation pulse
The product x obtained by multiplying every s by the memory address y1 (or y2) of the memory 5 where the vibration signal is stored is set as a new memory address, and the data stored in the original memory address is updated based on it. The process of moving to a new memory address is performed. This new memory address x becomes a pseudo memory address equal to the memory address of the memory 5 where vibration signal data is stored in the case of a standard rotation period. The value of this new memory address x is rounded off to the nearest whole number and converted into an integer. Due to this rounding, when the original memory address is changed to a new memory address, there may be a jump in the designation of the new memory address, or there may be overlap in the designation of the new memory address. That is, as shown on the left side of FIG. 5, when processed data of a vibration signal generated at a rotation period of 80 ms is stored in the original memory address y1 of the memory 5, the conversion process to a new memory address is performed. Then, the original memory address 1 becomes (1
00/80) x 1 = 1.25, rounding off the decimal point to the new memory address 1, and the original memory address 2 to 2.5
The original memory address 3 becomes the new memory address 4, the original memory address 4 becomes the new memory address 5, and the original memory address 5 becomes the new memory address 6. Then, the original memory address 6 becomes the new memory address 8... and the new memory addresses 2, 7, 12, 17, 2
A jump in memory address designation occurs at 2, 27, 32, . . . . Even if data is moved from the original memory address to a new memory address, no data is moved to this memory address where the jump occurred. In such a case, the same data as that stored at the immediately previous memory address is stored. On the other hand, as shown on the right side of FIG. 5, when the processed data of the vibration signal generated at a rotation period of 120 ms is stored in the original memory address y2, and the conversion process to a new memory address is performed, the original Memory address 1 is (100/120) x 1
=0.833..., round the decimal point to the new memory address 1, the original memory address 2 to the new memory address 2, the original memory address 3 to the new memory address 3,
The original memory address 4 becomes the new memory address 3, the original memory address 5 becomes the new memory address 4, the original memory address 6 becomes the new memory address 5, etc., and the new memory address 3 becomes
, 8, 13, 18, 23, 28, . . . overlapping memory address specifications occur. In such a case, data is moved from the original memory address to a new memory address by overwriting the previously stored data with subsequent data.

The vibration signal data that has been subjected to the time interval changing process in the memory 5 by the memory management means 8 as described above is read out in the next output circuit 9 as one of the five peak waves for each rotation pulse. , and its vibration signal is shown in Figure 6 (a
) (b) The signal waveforms shown in (c) are shown. Same figure (
A) is a standard signal waveform obtained at the standard rotation period, and there is no change in the signal period (100 ms) and signal waveform even after the time interval changing process is completed. Also, in the same figure (b), the rotation period is 8.
This is the pseudo signal waveform finally obtained in the case of 0ms,
After the time interval change process, the values of memory addresses 2, 7, 21, and 27 are the same as the previous memory address, so the signal waveform is slightly distorted compared to the standard signal waveform, but the period is different. There isn't. Similarly, in Fig. 6(c), the rotation period is 1.
This is a pseudo signal waveform read out by the output circuit 9 in the case of 20 ms, and after the time interval change processing, it is at memory address 3,
Since the data in No. 23 has been overwritten, the signal waveform is distorted compared to the standard signal waveform, but there is no difference in period between the two.

Therefore, if these signals are subjected to autocorrelation analysis processing in the next determination circuit 10, the period can be calculated even in the equipment of the variable speed rotation system 1, and the abnormal region can be specified. In this autocorrelation analysis, an abnormal period of vibration that occurs when an abnormality occurs in a certain part of the rotating system 1 at the standard rotation period is determined, and when the autocorrelation period matches such an abnormal period, This is to determine a specific part as an abnormal part. These determination results are displayed externally on a CRT screen or output to a printer.

[0023]

Effects of the Invention According to the method and apparatus of the present invention described in detail above, frequency analysis can be performed using a normal sampling method even in a rotating system whose rotational speed fluctuates or which operates while changing its rotational speed. The abnormality diagnosis of the equipment can be performed with high precision using the method and autocorrelation analysis method.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of a second inventive device related to an apparatus for implementing the method of the present invention.

FIG. 2 is a flowchart showing a processing procedure in this embodiment.

FIG. 3 is a waveform diagram showing a rotation pulse waveform.

FIG. 4 is a waveform diagram showing a vibration signal waveform subjected to envelope processing.

FIG. 5 is an explanatory diagram showing a method of specifying a new memory address in accordance with a memory address change performed in data time interval change processing.

FIG. 6 is a waveform diagram showing standard signal waveforms and pseudo signal waveforms read out after data time interval changing processing.

[Explanation of symbols]

1 Rotating system 2 Vibration detector 3 Envelope processing circuit 4 Pulse detection means 5. Memory 6 Period measurement means 7 Rotation period comparison means 8. Memory management means 9 Output circuit 10 Judgment circuit

Claims (3)

[Claims] Claim 1: When diagnosing an abnormality by detecting vibration of a variable speed rotation system, one of the displacement, velocity, and acceleration of the vibration is detected.
or more than one, together with the rotational speed of this rotating system,
When the acceleration of vibration is measured, the signal is passed through a high-pass filter to extract only the high-frequency components, and the measured vibration signals are rectified and subjected to envelope processing to obtain a constant sampling period. The processed vibration signal and rotation period signal are sampled as digital signals, and from the ratio of the preset standard rotation period and the rotation period of the rotating system, the vibration signal sampled at the same time as the rotation period signal is determined. A method for diagnosing an abnormality in a variable speed rotating system, characterized in that a time interval changing process is performed, and then an abnormal location or cause of the abnormality is determined by frequency analysis or autocorrelation analysis of the vibration signal subjected to the time interval changing process. 2. A vibration detector for detecting vibrations of a rotating system; an envelope processing circuit for rectifying and envelope processing a signal obtained from the vibration detector; A pulse detection means that detects one or more times, a memory that samples the envelope-processed vibration signal and the detected rotation pulse and stores them in paired areas, and an arbitrary rotation pulse that is stored in the memory. A period measuring means for measuring the period between pulses, a rotation period comparing means for calculating a ratio between a preset standard rotation period and a rotation period measured by the period measuring means, and an arbitrary rotation whose period has been measured. Converting the memory address of the memory where the vibration signal data paired with the pulse is stored to a new address according to the above ratio, moving the data in the memory to the memory at the new address, and changing the time interval of the data. A memory management means for processing, an output circuit for reading vibration signal data of the memory after movement for each rotation pulse, and a frequency analysis or autocorrelation analysis of the vibration signal based on the read data to detect abnormality in the rotation system. A variable speed rotation system abnormality diagnostic device comprising: a determination circuit that determines the location or cause of the abnormality. 3. In the variable speed rotation system abnormality diagnosis apparatus according to claim 2, in the data time interval changing process for converting the memory address and moving the data in the memory by the memory management means, the first address of the original address is used as the base point. The new memory address is determined by multiplying the relative address by the above-mentioned cycle ratio and converting it into an integer as the value of the relative address with the starting address of the new address as the base point. The data stored in the memory at the new address is stored in the memory at the new address, and if no data was moved from the memory at the original address in the memory at the new address, the same value as the data in the memory at the previous address is stored; 3. The variable speed variable speed converter according to claim 2, wherein when data in a memory at an address is stored in a memory at the same new address, later data is overwritten on the previously stored data. Rotating system abnormality diagnosis device.