JP3133423B2 - Abnormal detection device for rotating parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting an abnormality of a rotating part using acoustic emission (AE).

[0002]

2. Description of the Related Art Conventionally, as a device for detecting an abnormality of a rotating part using an AE, an AE sensor from a rotating part such as a bearing is detected by an AE sensor, and an AE signal from the AE sensor is compared with a fixed reference value. In some cases, when the AE signal exceeds the reference value, a display indicating an abnormality is made and the abnormality of the rotating component is detected.

[0003]

Generally, an AE caused by an abnormality of a rotating component occurs in synchronization with a rotation cycle of the rotating component. On the other hand, even when friction of the rotating component occurs during rotation of the rotating component, an AE having a longer duration than the AE caused by the abnormality of the rotating component occurs in synchronization with the rotation cycle.

[0004] As described above, A
Since the cycle of E coincides with the cycle of AE due to the friction of the rotating parts, the conventional abnormality detection device uses the A due to the friction of the rotating parts even when no abnormality has occurred in the rotating parts.
When the AE signal from the AE sensor that has detected E exceeds the reference value, the comparator outputs a signal indicating that there is an abnormality in the rotating component, and there is a problem that erroneous abnormality is detected.

Accordingly, an object of the present invention is to provide an apparatus for detecting an abnormality of a rotating part which can prevent erroneous detection of an abnormality when receiving AE due to friction of the rotating part and which can accurately detect an abnormality of the rotating part. To provide.

[0006]

According to the present invention, the duration of the AE signal due to the friction of the rotating part is substantially equal to the rotation period of the rotating part and longer than the duration of the AE signal due to the abnormality of the rotating part. Focusing attention, the AE signal due to the friction is extracted using a low-pass filter, and the AE signal is extracted as AE signal.
This is based on the consideration that the AE signal due to friction can be canceled by subtracting the AE signal from the sensor.

That is, the present invention provides an AE sensor for detecting an acoustic emission (AE) received from a rotating component and outputting an AE signal, receiving the AE signal from the AE sensor, and converting the AE signal into a frequency. Low A
A low-pass filter that outputs an AE signal obtained by attenuating an AE signal having a short duration by passing an E signal and attenuating an AE signal having a high frequency; and receiving the AE signal from the low-pass filter, Inverting means for outputting an inverted AE signal obtained by inverting a signal, the AE signal from the AE sensor and the inverted AE from the inverting means
Receiving the signal, and outputting a superimposed AE signal obtained by superimposing the AE signal and the inverted AE signal, and comparing the superimposed AE signal from the superimposing means with a reference value to determine whether the superimposed AE signal has a reference value. And comparing means for outputting an abnormality detection signal when the value exceeds the threshold value.

[0008]

AE from a rotating part such as a bearing is detected by an AE sensor and an AE signal is output. After appropriately processing the AE signal, the AE signal having a short duration among the AE signals is attenuated by the low-pass filter. For this reason, an AE signal generated by the friction of the rotating component and corresponding to the AE due to the friction having a long duration is output from the low-pass filter. On the other hand, the AE signal corresponding to the AE caused by the abnormality of the rotating component and having a short duration is attenuated by the low-pass filter and is not substantially output.

The AE signal from the low-pass filter is
The inverted AE signal is output by the inverting means.

Then, the inverted AE signal from the inverting means and the AE signal from the AE sensor which does not pass through the low-pass filter and the inverting means are superimposed on each other in phase by the superimposing means. As a result of the superposition, the AE signal from the AE sensor is canceled by the inverted AE signal.

Then, the superimposition means outputs a superimposed AE signal generated by the superposition. The superimposed AE signal is compared with a predetermined reference value by comparing means, and an abnormality detection signal is output when the superimposed AE signal exceeds the reference value.

As described above, the comparison means uses the AE caused by friction.
Since the superimposed AE signal in which the signal is canceled is compared with the reference value, malfunction of abnormality detection such as outputting an abnormality detection signal due to AE caused by friction of the rotating component when no abnormality occurs in the rotating component. Is prevented.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an apparatus for detecting an abnormality of a rotating part according to the present invention.

FIG. 1 is a block diagram showing an embodiment of an apparatus for detecting abnormality of a rotating part according to the present invention.
Is a preamplifier, 3 is a bandpass filter, 4 is a main amplifier, and 5 is an envelope detection circuit. 6 is a low-pass filter, 7 is an inverter, 8 is a mixer as superimposing means,
9 is an A / D converter, 10 is a computer, and 11 is a delay circuit. Further, the computer constitutes a comparison unit.

The AE sensor 1 detects an AE from a rotating component such as an inner ring of a bearing, and detects an AE indicating the size of the AE.
Outputs the E signal. After the AE signal from the AE sensor 1 is amplified by the preamplifier 2, an AE signal in a band of, for example, 200 kHz to 500 kHz is passed through the band pass filter 3 to remove noise. The AE signal from which noise has been removed by the band-pass filter 3 is transmitted to the main amplifier 4.
Are further amplified and input to the envelope detection circuit 5 for envelope detection. The envelope detected AE signal has, for example, as shown in FIG. 2 (A), the same period as the rotation period of the rotating component due to the abnormality of the rotating component, and has a relatively short duration T1. And an abnormal AE signal X having a period equal to the rotation period of the rotating component due to friction of the rotating component and having a relatively long duration. Note that the amplitude “0” shown in FIG. 2 is not an absolute value “0db” but an arithmetic “0” or “0” as a reference value (threshold).

In the AE signal, the abnormal AE signal X having a shorter duration than the friction AE signal is greatly attenuated by the low-pass filter 6, while the friction AE signal Y having a long duration is hardly attenuated. As shown in FIG. 2B, the low-pass filter 6 outputs substantially only the friction AE signal Y. The friction AE signal Y is inverted by the inverter 7 and the inverted friction AE shown in FIG.
A signal is output.

On the other hand, FIG. 2A after the envelope detection is performed.
After the AE signal shown in FIG. 8 is made to coincide in phase with the inverted friction AE signal by the delay circuit 11, the mixer 8
Thus, the signal is superimposed on the inverted friction AE signal shown in FIG.

By this superposition, the friction AE signal Y included in the AE signal shown in FIG. 2A is canceled by the inverted friction AE signal.

Then, the mixer 8 outputs a superimposed AE signal generated by the superposition and in which the friction AE signal Y is canceled. That is, as shown in FIG. 2 (D), the mixer 8 outputs the abnormal AE caused by the abnormality of the rotating component.
Only the signal X is output.

The abnormal AE signal X is input to a computer 10 via an A / D converter 9 and subjected to signal processing including FFT (Fast Fourier Transform) analysis before being compared with a predetermined reference value. . The computer 10 detects the abnormality A
An abnormality detection signal is output when the E signal X exceeds the reference value.

As described above, the computer 10 detects the abnormality A
Since only the E signal X is compared with the reference value, it is possible to prevent malfunction of malfunction detection such as outputting a malfunction detection signal due to AE caused by friction of the rotating component when no malfunction of the rotating component occurs, Abnormality of rotating parts can be accurately detected.

[0022]

As is apparent from the above description, in the apparatus for detecting an abnormality of a rotating part according to the present invention, the low-pass filter removes an abnormal AE signal caused by an abnormality of the rotating part from among the AE signals from the AE sensor, and A friction AE signal having a long connection time due to the friction of the parts is output, a reversing means outputs a friction AE signal obtained by inverting the friction AE signal, and a superimposing means outputs the inverted friction AE signal and the AE from the AE sensor.
A superimposed AE signal obtained by superimposing the signal is output. Then, the comparing means compares the superimposed AE signal in which the friction AE signal has been canceled by the superimposition with a predetermined reference value, and outputs an abnormality detection signal when the superimposed AE signal exceeds the reference value.

As described above, according to the present invention, the comparing means compares the superimposed AE signal from which the friction AE signal has been canceled with the reference value. Malfunction of malfunction detection such as outputting a malfunction detection signal due to AE caused by friction of
Abnormality of rotating parts can be accurately detected.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of a rotary component abnormality detection device according to the present invention.

FIG. 2 is a waveform chart showing a signal processing process of an AE signal in the embodiment.

[Explanation of symbols]

Reference Signs List 1 AE sensor 2 Preamplifier 3 Band pass filter 4 Main amplifier 5 Envelope detection circuit 6 Low pass filter 7 Inverter 8 Mixer 9 A / D converter 10 Computer 11 Delay circuit X Abnormal AE signal Y Friction AE signal

Claims (1)

(57) [Claims] An AE sensor for detecting an acoustic emission (AE) received from a rotating component and outputting an AE signal; and receiving the AE signal from the AE sensor to receive the AE signal.
By passing low-frequency AE signals from the signal and attenuating high-frequency AE signals, short-duration AE signals are obtained.
A low-pass filter that outputs an attenuated AE signal; an inverting unit that receives the AE signal from the low-pass filter and outputs an inverted AE signal obtained by inverting the AE signal; and an AE signal from the AE sensor. Receiving a signal and the inverted AE signal from the inverting means, and outputting a superimposed AE signal obtained by superimposing the AE signal and the inverted AE signal; Compared to,
An abnormality detection device for a rotating component, comprising: comparison means for outputting an abnormality detection signal when the superimposed AE signal exceeds a reference value.