JPS6312244B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vibration monitoring device for rotating machinery.

In most conventional vibration monitoring devices, a method is used in which the amplitude of vibration is measured and the vibration state is determined to be abnormal when the amplitude exceeds a certain threshold. Although this method is simple, it is difficult to appropriately determine threshold values depending on various rotating devices and load conditions, so it is difficult to know the occurrence of an abnormality in detail and with high accuracy. For this reason, a method is used to determine whether the vibration state is good or bad in detail by further analyzing the vibration frequency.

However, the frequency analysis device is not only quite expensive and complicated to handle, but also may not be suitable for use depending on the characteristics of the target vibration. Therefore, except in cases where the vibrations of a large, high-speed rotating machine are constantly monitored, a method of monitoring only using a threshold value of vibration amplitude is common.

The present invention has been made based on the above-mentioned matters, and in continuously monitoring vibrations of rotating machinery,
It is an object of the present invention to provide a vibration monitoring device that is relatively inexpensive and can perform detailed monitoring.

In monitoring the vibration of rotating equipment, the present invention calculates the amplitude distribution of data obtained as a vibration signal of the rotating equipment, and calculates the likelihood or population when this amplitude distribution is approximated as a normal distribution. The present invention is characterized in that an abnormality in the vibration state is identified based on this index.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a vibration monitoring device according to the present invention. In the figure, 1 is a rotating device to be monitored. A detector 2 for detecting vibration or acceleration is attached to this rotating device 1. This detection signal is amplified by an amplifier 3, and after a low frequency drift is removed by a high-pass filter 4, it is input to an arithmetic unit 5. This input signal is subjected to calculation in the calculation unit 5 according to the calculation procedure set from the calculation function setting device 6, and is further judged by the judgment means set from the judgment function setting device 8. An abnormality in the vibration state is identified, and the quality of the result is displayed on the display 9.

FIG. 2 shows a configuration in which a microcomputer is used as the arithmetic unit 5 in FIG. 1. In this figure, the same reference numerals as in FIG. 1 indicate the same parts. Reference numeral 11 denotes a sample and hold device that samples and holds the detection signal from the detector 2 that has passed through the amplifier 3 and the bypass filter 4;
is an analog-to-digital converter (AD converter). 13 is a DMA controller for direct memory access (DMA) of the detection signal. 14 is a random access memory (RAM) for temporarily storing the DMAed detection signal. 15 is a central processing unit (CPU). 16a
-16c is a read-only memory (ROM) for storing programs. A calculation program is stored in the ROM 16a, a determination program is stored in the ROM 16b, and a display program is stored in the ROM 16c. 17a to 17c are peripheral interface adapters (PIA). PIA17a is for connection with calculation function setting device 6,
PIA17b is for connection with judgment function setter 8, PIA
17c is for connection with the display 9. 18 is a bus.

The operation of the vibration monitoring device of the present invention described above will be explained in detail.

As shown in FIG. 3, the detection signal from the detector 2 is sampled by the sample-hold device 11 at regular intervals Δt, and the amplitude value at that point is
x ₀ , x ₁ , . . . are AD converted by the AD converter 12 and stored in the RAM 14 of the microcomputer. Since this operation may have a short sampling period, it is performed by DMA controlled by the DMA controller 13. In RAM14,
n pieces of amplitude value data are stored during measurement time T=(n-1)Δt.

This data is processed by the CPU 15 using the calculation program from the ROM 16a, and
The amplitude distribution is created as shown in the figure. in general,
If the vibration condition is normal, the amplitude distribution at that time is
It is reasonable to assume that it follows a normal distribution. Therefore, in this case, this can be expressed by a normal distribution N (μ ₁ , σ ² ₁ ) with mean μ ₁ and variance σ ² ₁ as parameters. This normal distribution N (μ ₁ , σ ² ₁ ) is stored in the RAM 14 as a normal distribution in a normal vibration state.

Next, a first method for determining abnormality in the vibration state will be explained. Let N (μ ₁ , σ ² ₁ ) be the amplitude distribution in a normal vibration state. If the vibration condition becomes abnormal, for example if the inner surface of the rolling bearing is damaged or if the gears do not fit properly,
The amplitude distribution of the vibration generated based on this is as shown in Figure 5, which is the normal amplitude distribution N(μ ₁ , σ ² ₁ )
The distribution deviates from, for example, N. A likelihood for a normal distribution is defined based on this distribution, and an abnormality is determined based on this likelihood. Therefore,
The vibration monitoring device determines whether the amplitude distribution is close to the normal distribution using the likelihood with respect to the normal distribution as an index, and determines an abnormality. In this judgment method, in any vibration state, the quality is judged simply based on the likelihood with respect to the normal distribution, so there is no need to prepare judgment criteria in advance. In addition, since it is possible to judge whether the vibration state is good or bad at each time point based on the likelihood at each time point, it is possible to judge the current vibration state or how it will change in the future. You can figure out what you are trying to become.

FIGS. 6 and 7 show a second method for determining abnormality in the vibration state.

In FIG. 6, the amplitude distribution in a normal vibration state is assumed to be N(μ ₁ , σ ² ₁ ). If the vibration condition becomes abnormal, for example if the inner surface of the rolling bearing is damaged or if the contact of the gear becomes poor, this amplitude distribution will deviate from the normal amplitude distribution shown by the solid line. , for example, the distribution is as shown by the dotted line. Assuming that this distribution is a normal distribution and estimating the population, the mean value μ ₂ and the variance σ ² ₂ are obtained. For the mean value μ ₂ , μ ₂ > μ ₁ holds true, and the variance σ ² ₂
It is expected that σ ² ₂ >σ ² ₁ holds true for σ 2 2 >σ 2 1.
Therefore, the vibration monitoring device determines the magnitude of this parameter to determine an abnormality. For this reason, the average value μ and the variance σ ² are determined based on normal vibration conditions, for example, data after the start of operation, and based on these, the determination criteria as shown in FIG. 7 are created. In FIG. 7, a case where the average value μ and the variance σ ² exceed a certain value is determined to be abnormal. Furthermore, by observing the vibration state in time series over a long period of time, it is possible to understand how the vibration state shifts from a normal state to an abnormal state using the parameters described above. Therefore, by referring to the determination criteria as shown in FIG. 7, it is possible to understand what the current vibration state is or what the vibration state is going to be in the future.

FIG. 8 is a flowchart illustrating the operation of the vibration monitoring device of the present invention.

First, the DMA controller 13 samples a vibration or acceleration detection signal as shown in FIG. 3 and stores it in the RAM 14. In this case, using the reference signal of the rotation angle, there is a method of inputting a fraction or one period thereof, or a method of inputting several periods in a superimposed manner. Based on this data, an amplitude distribution as shown in FIG. 4 is created. Hereinafter, abnormalities in the vibration state are determined by the method shown in FIG. 5, FIG. 6, or FIG. 7.
For each method, calculation function setting device 6, judgment function setting device 8
By setting the above, the CPU 15 can perform necessary calculations and judgments, and modify the calculation contents and judgment criteria without departing from the scope of the present invention. The determination result, for example, abnormality, normality, or an indicator thereof, is displayed on the display 9.

As detailed above, according to the present invention, compared to a method that measures only the amplitude of vibration and determines that the vibration state is abnormal when the amplitude exceeds a certain threshold, It is possible to know the occurrence in detail and with high accuracy. Furthermore, the device is simpler than a device that analyzes the vibration frequency to determine whether the vibration state is good or bad, and the calculation contents and determination method are simple and effective.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of one embodiment of the device of the present invention installed in a rotating machine, FIG. 2 is a block diagram showing the element configuration of an arithmetic unit used in the present invention, and FIG.
The figure shows a detection signal of the detector used in the device of the present invention, Figures 4 to 7 are explanatory diagrams showing a determination method based on amplitude distribution, and Figure 8 is a flowchart explaining the operation of the device of the present invention. It's a chat. 1...Rotating equipment, 2...Detector, 3...Amplifier, 4...Bypass filter, 5...Arithmetic unit, 6
...Calculation function setting device, 8...Judgment function setting device, 9
……display.

Claims (1)

[Claims] 1. A vibration monitoring device comprising an input means for inputting a vibration signal of a rotating device as data, and an abnormality identification means for identifying an abnormality in the vibration state based on the obtained data, wherein the abnormality identification means 1. A vibration monitoring device characterized in that an amplitude distribution of is obtained, a likelihood or a parameter when the amplitude distribution is approximated as a normal distribution is used as an index, and an abnormality in a vibration state is identified based on this index.