JP2915027B2 - Acoustic diagnosis method for rotating machines - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acoustic diagnosis method for a rotating machine that detects an acoustic signal of the rotating machine and diagnoses an abnormality of the rotating machine.

[Conventional technology]

Conventionally, the sound diagnosis method for rotating machines such as motors and gears has been carried out by bringing the rotating machine into an anechoic room or soundproof room with low background noise, or confirming that the effects of background noise can be ignored, and then using a sound level meter to measure the sound level. Was measured, and the diagnosis was made based on the level of the sound level, or the sound was analyzed with a narrow band frequency analyzer to make the diagnosis based on the level of a specific frequency.

Further, when the diagnosis cannot be made by the noise, the vibration corresponding to the noise generated from the machine is detected by the vibration pickup, and the diagnosis is made based on the magnitude of the vibration level or the magnitude of the vibration level at a specific frequency.

[Problems to be solved by the invention]

In the above-described conventional sound diagnostic technology using sound, since the rotating machine must be brought into an anechoic room or a soundproof room, it is not possible to perform 100% inspection on a mass production line.

An object of the present invention is to use a sound signal to detect a sound defect of a rotating machine,
It is an object of the present invention to provide a method capable of diagnosing at a site where background noise is large.

[Means for solving the problem]

The object is to rotate the rotating machine by a power supply device that supplies power to the rotating machine to be measured, a sound generated from the rotating machine is detected by an acoustic detector, and a rotating machine that analyzes the sound. In the acoustic diagnosis method, the acoustic diagnosis is performed by changing the frequency of the power supply device so that the vibration of the rotor constituting the rotating machine vibrates more than the vibration of the rotor when the rotating machine is rated. It is solved by that.

[Action]

By performing acoustic diagnosis while changing the frequency of the power supply device so that the vibration of the rotor that constitutes the rotating machine vibrates more than the vibration of the rotor when the rotating machine is rated,
The detection sensitivity can be improved.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to FIG.

FIG. 1 shows a block diagram of the present invention.
Is a rotating machine which is an object to be measured. Reference numeral 2 denotes a variable frequency power supply for driving the rotating machine 1. 3 turns on / off the power to the rotating machine 1
Switch circuit. Reference numeral 4 denotes an acoustic detector for detecting the sound generated from the rotating machine 1. Reference numeral 5 denotes a filter for analyzing a specific frequency component of an output signal from the acoustic detector 4. 6 is a filter 5
A square-law detection averaging circuit that converts the signal extracted in step 2 into a DC level. Reference numeral 7 denotes an A / D converter for converting the output of the square detection averaging circuit 6 into a digital signal. Reference numeral 8 denotes a microcomputer that controls the switch circuit 3 and the A / D converter 7 to measure acoustic data and diagnose the presence or absence of an abnormality based on the measurement result.

Reference numeral 9 denotes a zero-cross detection circuit that generates a signal when the voltage of the power supply supplied to the rotating machine 1 becomes zero.

The power supply 2 has a frequency of, for example,
The voltage is set to 0 V and supplied to the rotating machine 1 through the switch circuit 3.

The current I flowing through the stator of the rotating machine is given by I = V / 2πfL (V is the voltage applied to the stator, f is the frequency of the power supply, and L is the inductance of the stator). 100V
Applying 24 Hz f and 100 V V to the rotating machine designed according to the specifications, a large current flows, and the magnetic flux in the rotating machine saturates, so the rotor and stator of the rotating machine 1 are vibrated with a strong vibration force. As a result, a large vibration or sound is generated at the natural frequency of the rotor or the stator.

The sound is detected by the sound detector 4 and converted into an electric signal. The electric signal passes through a filter 5 preset at the frequency of the natural frequency of the rotor or the stator, and only a characteristic sound component is detected. Extract.

The acoustic signal that has passed through the filter 5 is applied to a square detection average circuit 6.
Is converted to a DC level by the A / D converter 7 and converted to digital by the A / D converter 7 and taken into the microcomputer 8 as acoustic data.

 FIG. 2 shows the time chart.

The power supply applied to the rotating machine 1 is intermittently applied as shown in FIG. 2, and an acoustic measurement is performed in a section where the voltage is applied.
Background noise is measured in a section where the voltage is cut off.

Since the sound of the rotating machine 1 is driven at a frequency lower than the steady state of 24 Hz, 100 V, a large current flows and the magnetic flux in the rotating machine saturates. An abnormal sound is generated in synchronization.

By extracting the abnormal sound component and performing A / D conversion at the timing of the zero-cross signal, the abnormal sound component of the sound can be measured efficiently.

Further, the background noise is measured in a section where the power is intermittently applied and the voltage is cut off, and the process of subtracting the background noise component data from the sound signal data is performed, so that the background noise can be corrected.

In the case of 24 Hz drive, the time of the sound measurement section and the background noise measurement section is about 83 ms.

The switching circuit can easily turn on and off the power supply by using the AC switching element shown in FIG. The zero-cross signal can be realized by a circuit as shown in FIG.

Further, as shown in FIG. 3, when the acoustic detector 4 is of a type in which two microphones and an arithmetic element are combined, the influence of background noise can be reduced. Hereinafter, the principle will be described.

The microphone A and the microphone B are shifted by the distance D and set. This distance D is set to be half the wavelength of the sound generated from the rotating machine.

The target sound coming from the front is converted into an electric signal by the microphone A, and becomes a solid line of the waveform (i). Also,
It is converted into an electric signal by the microphone B, and the waveform (i)
It becomes like the dotted line. At this point, the microphones are shifted by a half wavelength, so they are out of phase.

However, since the output of the microphone B passes through the inverting circuit 12, it has the same phase at the points C and D, and is added by the adder and emphasized like a waveform (v).

Background noise coming from around the microphone is microphone A
, The waveform (ii) is output as a solid line, and the microphone B is output as a dotted line of the same waveform. Background noise is A
Although the output of the microphone B is inverted at the points B and B, the phases are opposite at the points C and D, and when added by the adder 13, the respective waveforms cancel each other, and the waveform (vi) It becomes small like. That is, the background noise component input from the side of the microphone is canceled.

If the frequency of the acoustic signal is 2000 Hz, the half wavelength is 340
(M) / 2000/2 = 0.085 (m) = 85 (mm) and the distance D
Is 85 (mm).

 The cancellation effect is good from 600Hz to 2000Hz.

According to the experimental results, a cancellation effect of about 10 dB was obtained from 600 Hz to 2000 Hz.

According to the present embodiment, it is possible to perform acoustic diagnosis of a rotating machine even on a mass production line having relatively large background noise.

〔The invention's effect〕

The present invention is a rotating machine that rotates the rotating machine by a power supply device that supplies power to the rotating machine as an object to be measured, detects a sound generated from the rotating machine by an acoustic detector, and analyzes the sound. In the acoustic diagnosis method, the acoustic diagnosis is performed by changing the frequency of the power supply device so that the vibration of the rotor constituting the rotating machine vibrates more than the vibration of the rotor when the rotating machine is rated. It is characterized by the following. According to this configuration, it is possible to perform acoustic diagnosis of the rotating machine even in a place where the background noise is large.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a time chart of an acoustic measurement, FIG. FIG. 5 is a circuit diagram of the switch circuit shown in FIG. DESCRIPTION OF SYMBOLS 1 ... Rotating machine, 2 ... Power supply, 3 ... Switch circuit, 4 ... Sound detector, 5 ... Filter, 6 ... Square detection average circuit, 7 ... A / D
Converter, 8 ... microcomputer, 9 ... zero cross detection circuit, 10,1
1 ... Microphone, 12 ... Inverting circuit, 13 ... Adder, 14 ... AC switching element, 15 ... Photocoupler, 16 ... Transistor, 17 ... Resistance.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01H 17/00 G01M 19/00

Claims (4)

(57) [Claims] 1. A rotating machine for rotating the rotating machine by a power supply device for supplying electric power to the rotating machine as an object to be measured, detecting a sound generated from the rotating machine by an acoustic detector, and analyzing the sound. In the acoustic diagnosis method, the acoustic diagnosis is performed by changing the frequency of the power supply device so that the vibration of the rotor constituting the rotating machine vibrates more than the vibration of the rotor when the rotating machine is rated. An acoustic diagnostic method for a rotating machine, characterized in that it is performed. 2. The power supply device according to claim 1, wherein
The voltage of the power supply device is obtained from sound data generated from the rotating machine obtained by the acoustic detector when the voltage of the power supply device is turned on by a switch circuit that turns on and off.
A sound diagnosis apparatus for a rotating machine, wherein the sound diagnosis is performed by subtracting sound data generated from the rotating machine obtained by the sound detector in an OFF state. 3. The acoustic diagnostic apparatus for a rotating machine according to claim 1, wherein the timing of detecting the sound of the rotating machine by the acoustic detector is performed based on a zero-cross signal of the power supply device. 4. The sound detector according to claim 1, wherein the acoustic detector has two microphones, and the two microphones are separated from each other by a half of a wavelength of a sound generated from the rotating machine. A rotating machine for performing the acoustic diagnosis by adding a sound signal obtained on the one hand to an inversion circuit in the sound detector and adding the sound signal obtained on the other side of the microphone; Acoustic diagnostic equipment.