JPH0452526A - Tracking analyzer - Google Patents

Abstract

PURPOSE:To enable execution of an analysis of a multi-dimensional vibration component with excellent responsiveness by a method wherein a vibration signal of a rotating substance is subjected to A/D conversion and stored in a buffer memory and a processing of discrete Fourier transform is applied to a stored digital signal. CONSTITUTION:A vibration signal given to an input terminal 17 from a rotating substance to be measured is passed through an antialiasing filter 18 and subjected to A/D conversion 19 at a prescribed sampling frequency. A rotational pulse signal of the rotating substance is given to a control circuit 21 from an input terminal 20. Based on the rotational pulse signal, the circuit 21 outputs a data collection control signal S1 to the converter 19 and a buffer memory 22 while the rotating substance rotates in a prescribed number of times, and outputs a computation start instruction signal S2 to an arithmetic device 23. A digital signal outputted from the converter 19 is stored temporarily in the memory 22 while the signal S1 is outputted. With the signal S2 given, the device 23 executes a processing of discrete Fourier transform for the digital signal stored in the memory 22 and outputs the result of an arithmetic analysis. In this way, a component of 1 : (n) to the number of revolutions of vibration in a certain number of revolutions can be determined.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a tracking analysis device used for vibration analysis of rotating machinery, and more particularly to improvement of high-speed response tracking analysis of multi-order vibration components.

<Prior art> Generally, when measuring the vibration of rotating machinery, as shown in Figure 7, the magnitude of the vibration component (n-order component) at a frequency of n (n is an integer) relative to the rotational speed is calculated for each component. Tracking analysis is widely used to determine the relationship between rotational speed and vibration amplitude by measuring each rotation.

Conventionally, in such tracking analysis, a tracking filter is used as shown in FIG. 8, or a multiplication clock generation circuit and fast Fourier transform (FFT) processing are used as shown in FIG. 9.

In FIG. 8, a vibration signal from the rotating device 1 is detected by a vibration sensor (not shown) and is applied to each tracking filter 2, 3 corresponding to the signal component of interest. FIG. 8 shows an example in which a vibration component of 1 and a vibration component of 1:2 are analyzed with respect to the rotational speed. On the other hand, a pulse signal synchronized with the rotation of the rotating device 1 is detected by a rotation sensor (not shown) and is directly applied to the tracking filter 2 and f/V converter 4, and is also sent to the tracking filter 3 via a double multiplier 5. has been added to. The output signal of the tracking filter 2 is applied to the Y input terminal of the XY recorder 7 via the detector 6, and the output signal of the tracking filter 3 is applied to the Y input terminal of the XY recorder 9 via the detector 8. The output signal of the f/V converter 4 is applied to each X input terminal of the XY recorder 7.9.

With this configuration, the XY recorder 7 records vibration components with a ratio of 1:1 to the number of rotations, and the XY recorder 9 records vibration components with a ratio of 1:2 to the number of rotations.

In FIG. 9, a vibration signal applied to an input terminal 10 is applied to an A/D converter 12 via an anti-aliasing filter 11. On the other hand, the rotation pulse signal applied to the input terminal 13 is applied to the A/D converter 12 as a sampling clock via an M-times multiplier 14. A/
The vibration signal data converted by the D converter 12 is applied to the FFT calculation section 15 to calculate the vibration component. The calculation result of the FFT calculation section 15 is applied to a data processing/display device 16.

With this configuration, the data processing/display device 16 displays a vibration component of 1:n with respect to the rotational speed.

<Problems to be Solved by the Invention> However, when tracking filters are used as in the former configuration, as many filters as the orders desired to be measured simultaneously are required, and it is difficult to increase the number of orders to be measured.

In addition, according to the latter configuration, A/D
Since the sampling frequency of the converter also changes, in order to prevent aliasing it is necessary to use an anti-aliasing filter whose cutoff frequency can be changed according to the sampling frequency, which complicates the circuit configuration.

Furthermore, since the tracking filter and the multiplication clock generation circuit have a response delay, there is also the problem that they are unable to follow a sudden change in the rotational speed.

The present invention has been made with attention to these points,
The purpose is to provide a tracking analysis device that can perform tracking analysis of multi-order vibration components with a simple circuit configuration and with good responsiveness.

Means for Solving the Problems> The present invention to solve the above problems consists of an A/D converter that converts a vibration signal of a rotating object to be measured into a digital signal at a constant cycle that is sufficiently shorter than the rotation period of the rotating object to be measured. a D converter; a buffer memory that temporarily stores the digital signal converted by the A/D converter; and a buffer memory that stores the converted digital signal while the rotating object to be measured rotates a predetermined number of times. and a control circuit that performs control according to a rotation synchronization signal obtained from the rotating object to be measured; and an arithmetic unit that performs discrete Fourier transform processing on data stored in the buffer memory. It is something to do.

<Operation> According to the tracking analysis device of the present invention, the vibration signal of the rotating object to be measured is applied to the A/D converter and converted into a digital signal at a constant cycle, and the digital signal is temporarily stored in the buffer memory. Stored. The arithmetic unit then performs discrete Fourier transform (DFT) processing on the digital signal stored in the buffer memory.

This allows the circuit scale of the entire device to be relatively small,
Since the component circuit does not include response delay elements, measurements can be made without being affected even when the rotational speed changes rapidly.

<Example> Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. In the figure, input terminal 17 is connected to the rotating object to be measured (not shown).
To prevent aliasing, the vibration signal applied to A/
It is added to the D converter 19. The A/D converter 19 converts the vibration signal into a digital signal at a constant sampling frequency fs that is sufficiently higher than the rotational frequency of the rotating object to be measured. On the other hand, the rotation pulse signal of the rotating object to be measured is input to the input terminal 20.
from the control circuit 21. The control circuit 21 outputs a data collection control signal S1 to the A/D converter 19 and buffer memory 22 while the rotating object to be measured rotates based on the rotation pulse signal, and then outputs a calculation start instruction signal S2 to the calculation device. Output to 23. The digital signal converted and output by the A/D converter 19 is temporarily stored in the buffer memory 20 while the data collection control signal S1 is being output.

When the calculation start instruction signal S2 is applied, the calculation unit 23 performs a discrete Fourier transform (D
FT) Perform processing and output the calculation analysis results.

X(n); Number of rotations: Vibration component of n (n<L/2)
L: Number of data stored in the buffer memory K: Number of revolutions while storing data in the buffer memory Note that the anti-aliasing filter 18 uses an oversampling type A/D converter 19 such as a delta-sigma type. It can be omitted if necessary.

FIG. 2 is a timing chart showing the operation of FIG. 1. In Fig. 2, to simplify the explanation, it is assumed that the rotation pulse signal is output once every rotation of the rotating object to be measured, and data collection is performed while the rotating object to be measured rotates once. . That is, it is set as K-1.

■When the rotation pulse shown in (A) is input to the input terminal 20, the control circuit 21 outputs the data collection control signal S shown in (B).
1 is output to the A/D converter 19 and buffer memory 22.

(2) The A/D converter 19 performs A/D conversion at a constant sampling frequency fs shown in (D) by applying the data acquisition control signal S1, and sequentially stores the converted digital signals in the buffer memory 22.

(2) When the next rotation pulse is input after time T has elapsed, the rotating object to be measured has made one revolution, and the control circuit 21 stops the data collection control signal S1.

■When the data collection control signal S1 stops, the A/D converter 19
And the buffer memory 22 also stops operating.

(2) Subsequently, the control circuit 21 outputs a calculation start instruction signal S2 shown in (C) to the calculation device 23. The arithmetic unit F23 performs the above-mentioned DFT on the data stored in the buffer memory 22 upon receiving the arithmetic start instruction signal S2.
Execute processing.

(2) When the DFT processing is completed, the arithmetic unit 23 outputs the analysis result as shown in (E).

By the above procedure, it is possible to obtain the l:n component for the rotational speed of vibration at a certain rotational speed.

Therefore, by repeating the above procedure while changing the number of rotations, the tracking analysis results shown in FIG. 7 can be obtained.

With this configuration, the A/D converter 19 operates at a constant sampling frequency fs, so there is no need for a conventional multiplication clock generation circuit, and the cutoff frequency of the antialiasing filter 18 can be fixed. As a result, the circuit scale can be reduced compared to the conventional example.

Furthermore, since the component circuit does not include a tracking filter or a multiplier that has a response delay with respect to a change in the rotational speed, measurement can be performed without being affected even when the rotational speed changes rapidly.

In addition, in the timing chart of FIG. 2, A/D converter 1
9 is A only while the data collection control signal S1 is applied.
Although we have explained an example in which A/D conversion is performed, the A/D converter 19 is always operated as shown in FIG. 3(F), and the data collection control signal S1 is applied as shown in FIG. Data may be stored in the buffer memory 22 only while the user is there.

Furthermore, although the embodiment shown in FIG. 1 shows an example in which there is one arithmetic device 23, as shown in FIG.
By using 32, it is possible to calculate and output the component of the number of rotations ○ and the component of the number of rotations 1:m (n≠m) at the same time, thereby increasing the processing speed.

Furthermore, although the embodiment shown in FIG. 1 shows an example in which the number of vibration signal inputs is one system, as shown in FIG. selectively via A/
Alternatively, as shown in FIG. 6, multiple systems (18+, 18□, 191, 192) of anti-aliasing filter 18 and one A/D converter are provided and these are operated in parallel. By storing each output signal in the buffer memory 22, multiple systems of vibration signals can be measured.

<Effects of the Invention> As described in detail above, according to the present invention, it is possible to provide a tracking analysis device that can perform tracking analysis of multi-order vibration components with good responsiveness with a simple circuit configuration.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG. 2 is a block diagram of an embodiment of the present invention.
FIG. 3 is a timing chart explaining another example of the operation shown in FIG. 1. FIGS. 4 to 6 are block diagrams showing other embodiments of the present invention. , FIG. 7 is an explanatory diagram of tracking analysis, and FIGS. 8 and 9 are block diagrams each showing a configuration example of a conventional device.

Claims (1)

[Scope of Claims] An A/D converter that converts a vibration signal of a rotating object to be measured into a digital signal at a constant cycle that is sufficiently shorter than a rotation period of the rotating object to be measured; a buffer memory that temporarily stores the converted digital signal; and a buffer memory that stores the converted digital signal in the buffer memory while the rotating object to be measured rotates a predetermined number of times. A tracking analysis device comprising: a control circuit that performs control according to a synchronization signal; and an arithmetic unit that performs discrete Fourier transform processing on data stored in the buffer memory.