JPH0335609B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a vibration/noise analysis device for a rotating machine.

[Technical background of the invention and its problems]

Conventionally, various devices for analyzing vibrations and noise of rotating machines have been known, and some of them are constructed by a combination of analog circuits and digital circuits. In any case, in that case, phase analysis and frequency analysis were performed individually without using each other's data. Therefore, for example, the data obtained from phase analysis is only phase data, and frequency analysis has not been performed using the phase information.

[Purpose of the invention]

An object of the present invention is to provide a novel vibration/noise analysis device for a rotating machine that can share data for phase analysis and frequency analysis.

[Summary of the invention]

The vibration/noise analysis device of the present invention samples a vibration/noise signal, performs A/D conversion, and calculates the phase of each sampling point from the output signal into two sampling values: the sampling point and a phase point 90° ahead of the sampling point. further decompose each sampled value into a real part and an imaginary part using the phase,
This system is characterized in that the real part and the imaginary part are used to perform complex fast Fourier transform and perform frequency analysis.

[Embodiments of the invention]

FIG. 1 shows an embodiment of the present invention.
Vibration or noise of the rotating machine 10, for example vibration, is generally detected by n vibration sensors 11a, 11b,...11n.
is measured at n locations. The output electric signals of these vibration sensors 11a to 11n are inputted as parallel signals to the multiplexer 12, and outputted from there as serial signals and inputted to the A/D converter 13. The digital output signal of the A/D converter 13 is guided to a microcomputer comprising phase analysis means 15 and below. This microcomputer processes data for each vibration sensor, but in the following explanation, for simplicity, we will proceed with the assumption that there is only one vibration sensor. The multiplexer 12 functions as a sampling means as described below. A rotation pulse from a rotation pulse generator 14 that generates one pulse/rotation in synchronization with the rotation of the rotating machine 10 is also input to the phase analysis means 15 .
The phase analysis means 15 obtains the phase of each sampling point, and using the obtained phase, the complex calculation means 16 decomposes the sampling value at the phase point into a real part and an imaginary part. The data group consisting of the real part and the imaginary part obtained in this way is subjected to complex fast Fourier transform by the frequency analysis means 17 to perform frequency analysis, and the analysis result is displayed on the display device 18.

FIG. 2a shows the rotational pulse output from the rotational pulse generator 14 and a digital signal, that is, a sampling value, for a specific vibration sensor outputted from the A/D converter 13, and FIG. 2b shows the rotational pulse and It shows the data structure of a memory that stores sampling values. The rising edge of the rotation pulse is detected and stored as bit information together with the sampling value. The sampling frequency is determined depending on the phase analysis accuracy. For example, if you want to achieve a phase analysis accuracy of less than 1 degree by assuming that the rotation pulse interval is 360 degrees in one cycle, the number of sampling points in one cycle is, for example, 2 ⁹ = 512. It is sufficient to set it so that it is approximately 50×500 with a rotating machine of 50rps = 3000rpm.
= 25 x 10 ³ Hz = 25 KHz sampling frequency is sufficient. Sampling values are shown in figure b.
As shown in the figure, a data structure is created with bit information indicating the rise of rotation, that is, a rotation pulse is assigned to the uppermost bit of the data to form a data structure that indicates the presence or absence of a rotation pulse. Figure 2 shows the sampling order N ₁ that coincides with the first rotation pulse generation.
Starting from , the sampling order is N ₁ +1,
Sampling is performed as N ₁ +2, ..., and the sampling order is set at the same time as the second rotation pulse generation.
The sampling order from N ₂ to the next sampling order N ₂ +1 is illustrated. Each sampled value is recorded in, for example, 12 bits, or 2 ¹² =4096 steps.

The data processing procedure performed by the phase analysis means 15 and below will be explained below with reference to the flowchart of FIG. First, the rotation pulse and sampling value Z(n) are stored in the memory shown in Fig. 2b.
(where n=1, 2, 3, . . . n) is read (step 3a). The order of the sampling value having the bit information of the first rotation pulse is set to _N1 (step
3a), the order of sampling values having bit information of the next rotational pulse is set to _N2 (step 3c). The interval between both rotation pulses is 1 cycle (1 rotation) = 360°
Then, the number of samplings between sampling points corresponding to a phase difference of 90° is determined by (N ₂ −N ₁ )/4, and this is set as m (step 3d). next,
From the sampling value Z (N ₁ ) of _one point in rank N and the m-th sampling value Z (N ₁ +m) from now on,
Find the phase θ (N ₁ ) of vibration and noise at one point N using _the following formula.

θ(N ₁ )=tan ^-1 Z(N ₁ +m)/Z(N ₁ ) Generally, the sampling value at point N is Z(N)
Then, the phase θ(N) at point N is found as θ(N)=tan ^-1 Z(N+m)/Z(N) (step 3h). This phase θ(N)
The real part X(N) and the imaginary part Y(N) of the sampling value Z(N) at each sampling point are determined using the following equations (step 3i).

X(N) = Z(N)・cosθ(N) Y(N)=Z(N)・sinθ(N) The above steps 3h and 3i are ranked from N ₁ to N ₂ or higher, for example, at the sampling interval as described above. To set the angle to about 1°, repeat until the number of sampling points N ₀ =2 ⁹ =512 (steps 3e, 3f to 3j). When this number of sampling points is exceeded, complex fast Fourier transform is performed on it using the real part X(N) and imaginary part Y(N) obtained in step 3i, and frequency analysis is performed to extract the fundamental wave and each harmonic. The real part Fr(n) and imaginary part Fi(n) of each included frequency component are determined (step 3k). Then, for each frequency, the real part
Using Fr and the imaginary part Fi, find the power spectrum from the following equation (step 3l).

(Fr ² +Fi ² )/No Next, the results obtained in step 3h and step 3l are displayed on the display device 1 in the form of a table and/or graph.
8. For example, display on a monitor display (step 3m).

〔Effect of the invention〕

As described above, the present invention performs phase analysis from vibration/noise sampling signals and rotational pulse information, and uses the phase information to perform frequency analysis by complex fast Fourier transform, so it is completely digital processing. , and data can be reused.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention;
2a and 2b are graphs and data configuration diagrams showing the relationship between rotational pulses and sampling values, and FIG. 3 is a flow chart for explaining the operation of the apparatus shown in FIG. 1. 10... Rotating machine, 11a to 11n... Vibration sensor, 12... Multiplexer, 13... A/D converter, 14... Rotating pulse generator, 15... Phase analysis means, 16... Complex calculation means , 17... frequency analysis means, 18... display device.

Claims (1)

[Claims] 1 A sensor that detects vibration or noise of a rotating machine and converts it into an electrical signal, a sampling means that samples the output signal of this sensor at a predetermined sampling frequency, and an A/D converter that converts the output signal of this sampling means from A/D. A D converter, a rotation pulse generator that generates a rotation pulse signal every rotation of the rotary machine, and one cycle between two adjacent rotation pulse signals generated by the rotation pulse generator. a phase analysis means that calculates the phase of each sampling point based on the output signal of the A/D converter using two sampling values of the sampling point and a phase point 90° ahead of the sampling point; complex calculation means for decomposing each sampled value into a real part and an imaginary part using the phase determined by the phase analysis means; 1. A vibration/noise analysis device for a rotating machine, comprising: frequency analysis means for performing frequency analysis by performing complex fast Fourier transform.