JPH06217576A - Device for inpecting abnormality of rotary machine - Google Patents

Abstract

PURPOSE:To reduce the inspecting time of a rotary machine device and, at the same time, to improve the inspecting accuracy by detecting the acoustic pressure and vibration of the rotary machine for a fixed period of time and counting the number of peaks exceeding a reference value in the time- and frequency-domains, and then, detecting the abnormality of the rotary machine based on each peak count. CONSTITUTION:The acoustic pressure and vibration of a rotary machine 1 are detected by means of detecting means 2 and 3. A standard deviation calculating means 4 calculates the standard deviations of detected acoustic pressures L' and detected vibrations M' at every rotational cycle and discriminates that no disturbance, such as the external noise, etc., exists at the measuring time when the fluctuating widths of the standard deviations are within criteria. Then a counting means 5 counts the numbers LP' and MP' of peaks exceeding reference values of the detected acoustic pressures L' and detected vibrations M' in the time-domain and another counting means 6 counts the numbers AP' and BP' of peaks exceeding the reference value of power spectrum density of the L' and M' in a specific frequency band by analyzing the L' and M' for frequency. Thereafter, a discriminating means 7 discriminates the abnormality of the rotary machine 1 based on the numbers of peaks LP', MP', AP' and BP'.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotating machine abnormality inspection apparatus which is suitable for checking whether or not there is an assembly abnormality in an alternator which is a vehicle generator.

[0002]

2. Description of the Related Art FIG. 9 shows, for example, Japanese Patent Laid-Open No. 1-234083.
It is a figure which shows the structure of the abnormality inspection apparatus of the conventional rotary machine shown by the publication. In the figure, 10 is an alternator to be inspected, 13 is a driving device of the alternator 10, and 15
Is a rotation speed sensor for detecting the rotation speed, and 20 is a microphone for detecting the pressure of the rotation sound. The detection signal from the microphone 20 is amplified by the amplifier 22, passes only a predetermined frequency component by the filter 24, and then processed by the effective value conversion circuit 26 and the logarithmic conversion circuit 28 to become a sound pressure signal.
On the other hand, the detection signal from the rotation speed sensor 15 is sent to the amplifier 16
Is amplified by the F / V converter 18 and converted into a voltage proportional to the frequency of the amplified signal by the F / V converter 18 to become a rotation speed signal. As shown in FIG. 10, the microcomputer 41 controls the drive device 13 so that the rotation speed of the alternator 10 linearly changes with the passage of time t, and at the same time, A / D converter 42-1 and From 42-2, a sound pressure signal and a rotation speed signal are input. Now, when the rotation speed N is represented by the X coordinate and the sound pressure L is represented by the Y coordinate, the response waveform indicated by the curve 1 shown in FIG. 11 is obtained. From the coordinate values (Xi, Yi) on this curve l, Y = a
A regression line P represented by X + b and a reference line Q obtained by shifting the regression line P upward by α dB are determined. The slope a of the regression line P
And the offset b are calculated by the following equations.

[0003]

[Equation 1]

After that, the area S where the curve 1 exceeds the reference line Q
Then, the rotation speed width ΔN is calculated, and when either exceeds an allowable limit value, it is determined that there is an abnormality, and the drive circuit 53 causes the display lamp 51 to display an abnormality.

[0005]

However, according to such a conventional abnormality inspection apparatus, since the regression line P and the reference line Q are determined from the sound pressure L corresponding to the number of revolutions N of the alternator 10, the alternator 10 is operated. The regression line P and the reference line Q change for each sample, and there is a problem that the quality of the alternator 10 obtained as a non-defective product is not stable even in the same model. In addition, it is not possible to detect minute abnormal sounds such as those caused by scratches or dust between the brush and slip ring,
There is a possibility that the abnormality may be mistakenly overlooked, or conversely, the determination result may be incorrect due to external noise or the like. In order to improve the inspection accuracy with the conventional abnormality inspection device against such problems, it is necessary to decrease the rate of change of the rotation speed N and increase the number of measurement points. However, the inspection time depends on the number of measurement points. Becomes longer,
A new problem occurs such as not meeting the line tact on the production line.

The present invention has been made to solve such a problem, and its object is to improve the inspection accuracy without prolonging the inspection time and to improve the quality of the rotating machine obtained as a good product. To stabilize.

[0007]

In order to achieve such an object, the first invention of the present application (the invention according to claim 1) is
As shown in FIG. 1A, first and second detecting means for detecting pressure and mechanical vibration of sound generated from the rotating machine 1 for a certain period of time when the rotating machine 1 is rotating at a predetermined rotation speed. 2 and 3, and the first and second detection means 2
In the time domain of the sound pressure and vibration detected by the first and second detecting means 2 and 3, and the standard deviation calculating means 4 for calculating the standard deviation of the sound pressure and the vibration detected by each rotation cycle. The first counting means 5 for counting the number of peaks exceeding the reference value of 1 and the first and second detecting means 2
Second counting means 6 for frequency-analyzing the sound pressure and vibration detected by 3 and 3, and counting the number of each peak exceeding the reference value of the power spectral density in a specific frequency band of the sound pressure and vibration, and a standard deviation. Assuming that the fluctuation range of the standard deviation calculated by the calculation means 3 is within the standard, the first
And a judging means 7 for judging an abnormality of the rotating machine 1 based on the number of peaks counted by the second counting means 5 and 6. The second invention (the invention according to claim 2) is, as shown in FIG. 1B, a first and second detecting means 2 and 3, a standard deviation calculating means 4, and a first and second detecting means. Assuming that the fluctuation range of the standard deviation calculated by the counting means 5 and 6 and the standard deviation calculating means 4 is within the standard, the peak number of each peak counted by the first and second counting means 5 and 6 When all the ratios with the respective reference peak numbers exceed the non-defective product level, the fluctuation range of the standard deviation calculated by the first judging means 7 ', which judges this as an abnormality of the rotating machine 1, and the standard deviation calculating means 4. If a part of the ratio of each peak number counted by the first and second counting means 5 and 6 to each reference peak number exceeds the non-defective level, the 1 and second detection means 2
The sound pressure and the vibration are re-detected by and 3, the standard deviation is recalculated by the standard deviation calculating means 4, and the respective peak numbers are re-counted by the first and second counting means 5 and 6, which are re-counted. When the ratio of the ratio of each peak number to each standard peak number exceeds the non-defective level is the same as the previous time, the second determination means 8 for determining this as an abnormality of the rotating machine 1 is provided.

[0008]

Therefore, according to the first aspect of the invention, in the first aspect of the invention, when the rotating machine 1 is rotating at a predetermined number of revolutions, the sound pressure and mechanical vibration generated from the rotating machine 1 remain constant for a certain period of time. It is detected by the first and second detecting means 2 and 3. Then, the sound pressure L'and the vibration M'detected by the first and second detecting means 2 and 3.
The standard deviation for each rotation cycle is calculated by the standard deviation calculating means 4. If the fluctuation range of the calculated standard deviation is within the reference, it can be determined that there is no disturbance such as external noise at the time of measurement. The first counting means 5 includes the respective peak numbers LP 'and M that exceed the reference values of the sound pressure L'and the vibration M'in the time domain.
Count P '. The second counting means 6 frequency-analyzes the sound pressure L'and the vibration M ', and the respective peak numbers AP' and BP exceeding the reference value of the power spectral density in the specific frequency band of the sound pressure L'and the vibration M '. 'Counts. The determination means 7 assumes that the fluctuation range of the standard deviation calculated by the standard deviation calculation means 4 is within the reference, and the respective peak numbers LP ′, MP ′ counted by the first and second counting means 5 and 6. ，
The abnormality of the rotating machine 1 is determined based on AP 'and BP'.
In the second invention, the first invention is carried out in the same manner as the first invention.
And the second detecting means 2 and 3 detect the sound pressure L ′ and the vibration M ′, the standard deviation calculating means 4 calculates the standard deviation of the sound pressure L ′ and the vibration M ′, and the first and second counts are performed. Means 5 and 6 are for each peak number LP ', MP' and AP ',
Count BP '. The first judging means 7 ′, assuming that the fluctuation range of the standard deviation in the standard deviation calculating means 3 is within the reference, the number of peaks LP counted by the first and second counting means 5 and 6 Ratio Ln ', Mn', An ', Bn' of each of the reference peak numbers of ', MP', AP ', BP'
And the ratios are all good product levels Lt, Mt, A
If t and Bt are exceeded, this is determined as an abnormality of the rotating machine 1. The second determination means 8 uses the ratio Ln ′, M
Part of n ′, An ′, Bn ′ is a non-defective product level Lt, Mt,
When it exceeds At and Bt, the sound pressure and vibration are measured again, and the ratios Ln ′, Mn ′, An ′ and Bn ′ are measured again.
When the value exceeding the non-defective level is the same as the previous time, this is determined as an abnormality of the rotating machine 1.

[0009]

EXAMPLES The present invention will now be described in detail based on examples.

Embodiment 1 FIG. 2 is a block diagram showing an embodiment of the present invention, and shows an example in which an abnormality inspection device is applied to the alternator 10. This abnormality inspection device has a microphone 20 and an acceleration pickup 30, the motor 12 and the alternator 10 are connected by a coupling 16, and when the alternator 10 is rotating at a predetermined rotation speed, The presence or absence of abnormality is determined by detecting the pressure of generated sound and mechanical vibration for a certain period of time.

The sound pressure detected by the microphone 20 is amplified by the amplifier 22, passes through the filter 24 for removing disturbance such as noise, and enters the A / D converter 42 as a sound pressure signal.
Similarly, the vibration detected by the acceleration pickup 30 is
The signal is amplified by the amplifier 32, passes through a filter 34 for removing disturbance such as floor vibration, and enters the A / D converter 42 as a vibration signal.

The motor control unit 52 controls the motor 12 according to an instruction from the arithmetic control unit 40 so that the motor 12 has a predetermined rotation speed. The rotation speed of the motor 12 is detected by the encoder 14 attached to the motor 12, and when the rotation speed stabilizes at a predetermined rotation speed, the motor control unit 52 changes the calculation control unit 40.
A rotation completion signal is sent to.

Upon receipt of this rotation completion signal, the arithmetic control unit 40 sends a conversion start signal to the A / D converter 42 to perform analog / digital conversion of the sound pressure signal and the vibration signal for a certain period of time.
It is performed at a predetermined sampling interval. The sound pressure signal and the vibration signal converted into digital values are stored in the waveform memory 44 and then called up as needed in accordance with the arithmetic processing in the arithmetic control unit 40 and the signal processor 46.

The signal processor 46 executes at high speed signal processing such as frequency analysis of waveforms, which requires calculation time in the calculation control section 40. The processing content is pre-programmed in the ROM or downloaded from the calculation control section 40. Shall be done.

As a result of the arithmetic processing in the arithmetic control unit 40 and the signal processor 46, the presence / absence of abnormality of the inspected alternator 10 is displayed on the display unit 50 to inform the operator and other equipment of the determination contents.

Next, a method of creating a non-defective item determination standard will be described. First, the non-defective alternator 10 is connected to the motor 12, and the sound pressure signal and the vibration signal are measured for a predetermined time (n rotations) via the microphone 20 and the acceleration pickup 30.

FIG. 3 shows the sound pressure signal L and the vibration signal M input to the A / D converter 42. The data stored in the waveform memory 44 is A / D converted from the sound pressure signal L and the vibration signal M at each sampling time. The sample time is sufficiently shorter than one rotation time of the alternator 10, and even if the sampling is performed with discrete values, it is possible to reproduce up to the frequency band necessary for measuring the sound pressure and the vibration.

The measured sound pressure signal L and vibration signal M are divided for each rotation cycle to calculate standard deviations L1 to Ln and M1 to Mn. Now, the fluctuation widths ΔL and ΔM of the standard deviation value are calculated by the following equations,

[0019]

[Equation 2]

Within allowable limits Ls and Ms, respectively (ΔL <L
s, ΔM <Ms), it is assumed that the input data has no disturbance or the like, a standard deviation value is obtained over the entire measurement time, and the standard deviation value is tripled to obtain a peak determination reference value Ll in the time domain, Let Ml.

On the contrary, if the fluctuation widths ΔL and ΔM of the standard deviation values exceed the permissible limits Ls and Ms, there is a possibility that disturbance such as noise will be entered, so the sound pressure and vibration are input again.

After the peak judgment reference values Ll and Ml are determined, the number of peaks in which the absolute values of the sound pressure signal L and the vibration signal M exceed the judgment reference values Ll and Ml are counted, and the peak count value in the time domain is calculated. (Reference peak number) Lp and Mp are calculated.

In the frequency domain inspection, the measured frequencies of the sound pressure signal L and the vibration signal M are analyzed for each rotation of the alternator 10 and averaged to calculate the power spectral densities A and B with respect to the frequency (see FIG. 4). From the power spectral densities A and B, a specific frequency band, for example, F
The standard deviation value in the area of Fmax (Hz) from min (Hz) is obtained, and the standard deviation value is tripled to be the peak determination reference values Al and Bl in the frequency area.

After the peak judgment reference values Al and Bl are determined, the number of peaks at which the power spectral densities A and B of the sound pressure signal L and the vibration signal M exceed the judgment reference values Al and Bl are counted, and in the frequency domain. Peak count value (reference peak number)
Calculate Ap and Bp.

Finally, the peak count value Lp in the time domain,
Based on Mp and the peak count values Ap and Bp in the frequency domain, limit values (non-defective product levels) Lt, Mt and At, Bt that are considered to be non-defective products are set.

By the above method, the peak judgment reference value L
1, Ml, Al, Bl, peak count values Lp, Mp, A
p, Bp and limit values Lt, Mt, At, Bt are obtained in advance by using the non-defective item alternator 10 and stored in the memory of the arithmetic control unit 40 as non-defective item determination data. The stored non-defective item determination data is read for each inspection of the alternator 10, and the peak count value L of the sample item is read.
p ', Mp', Ap ', Bp' and non-defective peak count L
The ratio with p, Mp, Ap, Bp is calculated, and the limit value L
The quality is judged by comparing with t, Mt, At, and Bt.

Next, the inspection procedure will be specifically described. FIG. 7 is a flowchart showing the inspection procedure, and the processing according to this flowchart is executed by the arithmetic control unit 40 and the signal processor 46. In the figure, step 701
Then, the alternator 10 is replaced with an inspection product, and the sound pressure signal L ′ and the vibration signal M ′ are measured under the same conditions as when the non-defective product determination data is obtained.

In step 702, the measured sound pressure signal L'and vibration signal M'are divided for each rotation cycle, and the fluctuation widths ΔL ', ΔM' of the standard deviation value are calculated.

The fluctuation widths ΔL 'and ΔM' are allowable limits Ls and M.
If it exceeds s, disturbance such as noise may have entered, so in response to NO in step 703, step 701 is executed again.
Then, the sound pressure signal L ′ and the vibration signal M ′ are measured again.

That is, when the alternator 10 is an abnormal assembly product, an abnormal sound or vibration is generated in synchronization with the rotational position even if the abnormality is slight. Therefore, by examining the reproducibility of the waveform for each rotation period, it is possible to know the presence or absence of disturbance such as external noise or vibration with respect to the input data. In step 702, the reproducibility of the waveform is checked by calculating the standard deviation for each rotation cycle. In step 703, if the fluctuation range is outside the predetermined range, it is determined that the input is abnormal and the sound pressure and Re-enter the vibration.

In step 704, the number of peaks in which the sound pressure signal L'and the vibration signal M'exceed the peak judgment reference values Ll and Ml in the time domain are counted, and the peak count value L in the time domain is counted.
Calculate p'and Mp '.

In step 705, the sound pressure signal L'and the vibration signal M'are divided for each rotation, and the signal processor 4 is divided.
6, and the power spectral densities A ′ and B ′ are obtained.

In step 706, the specific frequency (Fmi
n to Fmax) power spectral densities A ′ and B ′ are
The number of peaks exceeding the peak determination reference values Al and Bl in the frequency domain is counted, and the peak count value Ap ′ in the frequency domain,
Calculate Bp '.

In step 707, the peak count values Lp, Mp, Ap, Bp of the non-defective product and the calculated peak count value L are calculated.
Ratio Ln ′, M with p ′, Mp ′, Ap ′, Bp ′
Calculate n ', An', Bn '.

Then, this ratio Ln ', Mn', A
By comparing n ', Bn' with the limit values Lt, Mt, At, Bt (steps 708, 710), Ln '≤ Lt, and M
If n ′ ≦ Mt, An ′ ≦ At, and Bn ′ ≦ Bt, the alternator 10 is normal (step 70
9), the inspection ends.

On the contrary, when the ratio is Ln '> Lt and Mn'>
If Mt, An '> At, and Bn'> Bt, it is determined that the alternator 10 is abnormal (step 71).
1), the inspection is completed.

If neither normal nor abnormal can be determined in steps 708 and 710, step 712
Proceed to. In step 712, the ratios Ln ′, Mn ′, A
After storing whether n ′ and Bn ′ are larger or smaller than the limit values Lt, Mt, At, and Bt in the memory, the process proceeds to step 714 via step 713 to update the counter for counting the number of inspections, and step 701. Return to and measure sound pressure and vibration again.

If the presence / absence of abnormality cannot be specified again in step 710, it is compared with the determination result previously stored in the memory in step 713. If the determination result for each inspection item is the same, It is determined that there is an abnormality (step 711). On the other hand, if the determination results are different, the measurement error is included, so the counter is updated again (step 714) and the process returns to step 701.

When the inspection is repeated due to NO in step 713, a new limit value for the number of inspections is set,
If the counter value in step 714 exceeds the limit value,
It may be determined that there is an abnormality.

If the presence / absence of abnormality can be specified in steps 710 and 713, an instruction is issued to the display section 50 to turn on the pilot lamp or the like.

FIG. 5 shows an example of the sound pressure signal L'and the vibration signal M'of the alternator 10 which is judged by the abnormality inspection apparatus of this embodiment to be abnormal, and FIG. 6 shows the sound pressure signal L'and the vibration signal M. The power spectral densities A'and B'of 'are shown.

In both FIGS. 5 and 6, the peak count values Lp ', Mp', Ap ', Bp' are clearly different from those of the non-defective product, and the abnormality can be easily detected. Further, even if the inspection was repeated, the inspection results did not differ, and the stability was good.

As described above, according to this embodiment,
Since the number of peaks exceeding the sound pressure and vibration reference values is counted in the time domain and the frequency domain to determine the quality of the alternator 10, abnormalities due to local scratches on the brush and slip ring, and changes in sound pressure. It is possible to detect even a small defect with a small change in vibration and a defect with a small vibration change with high accuracy without prolonging the inspection time. Also,
Since the determination standard is fixed for each model, the quality of the alternator 10 obtained as a good product can be stabilized. On the contrary, even for an abnormal product, it is possible to rank the abnormality level and specify the content of the abnormality, so that the time required for the repair work can be shortened.

Second Embodiment In the first embodiment, the number of revolutions of the alternator 10 and the frequency band to be inspected are set at one location, and a portion in which the characteristic difference between the good product and the defective product is most prominent is used in advance. The number of revolutions may be varied and measured several times, or a plurality of frequency bands to be inspected may be provided.

Third Embodiment Further, in the first embodiment, the microphone 20 is provided as a means for detecting sound pressure, and the acceleration pickup 30 is provided as a means for detecting vibration, respectively. However, as shown in FIG. Front side and rear side of the alternator 10,
A plurality of each may be provided, and in this case, it is possible to apply the method to specify the abnormal portion.

Embodiment 4 It should be noted that depending on the contents of the abnormality, only the sound pressure may be measured or only the vibration may be measured, and the respective detection means are not limited to the microphone 20 or the acceleration pickup 30.

Embodiment 5 Furthermore, the dedicated signal processor 46 was used to analyze the frequencies of the sound pressure signal and the vibration signal. However, if the inspection time does not cause a problem, the arithmetic control unit 40 may be used for the calculation. You may

Sixth Embodiment Further, the signal processor 46 can freely change the processing contents by a program similarly to the arithmetic control unit 40, so that it may be used as a digital filter other than the frequency analysis of the signal. In this case, the filter 24
And 34 can be omitted, and the cost can be reduced.

[0049]

As is apparent from the above description, according to the present invention, the sound pressure and vibration generated from the rotating machine are detected for a certain period of time while the rotating machine is rotating at a predetermined number of revolutions, and the reference value is set. The number of peaks that exceed is counted in the time domain and the frequency domain, and assuming that the fluctuation range of the standard deviation of sound pressure and vibration for each rotation cycle is within the standard, the abnormality of the rotating machine is determined based on each of the above peak numbers. Since it is detected, the inspection accuracy is improved without prolonging the inspection time.
The quality of the rotating machine obtained as a good product can be stabilized.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main part of the present invention.

FIG. 2 is a configuration diagram showing an embodiment of the present invention.

FIG. 3 is a diagram illustrating a sound pressure signal and a vibration signal in a time domain of a normal product.

FIG. 4 is a diagram illustrating sound pressure and vibration power spectrum densities in a frequency region of a normal product.

FIG. 5 is a diagram illustrating a sound pressure signal and a vibration signal in the time domain of an abnormal product.

FIG. 6 is a diagram exemplifying power spectral densities of sound pressure and vibration in a frequency region of an abnormal product.

FIG. 7 is a flowchart showing a process (inspection procedure) executed by an arithmetic control unit and a signal processor.

FIG. 8 is a configuration diagram showing another embodiment of the present invention.

FIG. 9 is a configuration diagram showing a conventional abnormality inspection device.

FIG. 10 is a diagram showing a speed pattern for driving an alternator in a conventional abnormality inspection device.

FIG. 11 is a diagram for explaining an abnormality determination operation of the conventional abnormality inspection apparatus that creates a regression line and a reference line.

[Explanation of symbols]

 10 Alternator 12 Motor 14 Encoder 20 Microphone 30 Accelerometer 40 Arithmetic Control Unit 42 A / D Converter 44 Waveform Memory 46 Signal Processor 52 Motor Control Unit

Claims (2)

[Claims] 1. A first and second detecting means for detecting a pressure and a mechanical vibration of a sound generated from the rotating machine for a certain period of time when the rotating machine is rotating at a predetermined rotation speed, and the first detecting means. And a standard deviation calculating means for calculating the standard deviation of the sound pressure and vibration detected by the second detecting means for each rotation cycle, and a time domain of the sound pressure and vibration detected by the first and second detecting means. And a first counting means for counting the number of peaks exceeding the reference value, and frequency analysis is performed on the sound pressure and vibration detected by the first and second detecting means, and the specific frequency band of the sound pressure and vibration is analyzed. The second counting means for counting the number of each peak exceeding the reference value of the power spectral density in the above, and the first deviation on the assumption that the fluctuation range of the standard deviation calculated by the standard deviation calculating means is within the reference. And Based on the number of peaks counted by the second counting means, abnormality inspection device for a rotary machine, characterized by comprising determination means for determining abnormality of the rotating machine. 2. The abnormality inspection device for a rotating machine according to claim 1, wherein the variation range of the standard deviation calculated by the standard deviation calculating means is within a reference instead of the determining means. When the ratio of each peak number counted by the first and second counting means to each reference peak number exceeds the non-defective level, the first determining means determines this as an abnormality of the rotating machine, and the standard Assuming that the fluctuation range of the standard deviation calculated by the deviation calculating means is within the standard, part of the ratio of each peak number counted by the first and second counting means to each reference peak number is If the quality level is exceeded, the sound pressure and vibration are detected again by the first and second detection means, and the standard deviation is calculated again by the standard deviation calculation means.
If the number of peaks is re-counted by the first and second counting means and the ratio of the re-counted peak number to the reference peak number exceeds the non-defective level is the same as the previous time, And a second determining means for determining that the abnormality is an abnormality of the rotating machine.