JP3513405B2 - Generator ripple spring looseness inspection device - 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 inspecting a ripple spring of a generator for looseness, and more particularly to an apparatus for inspecting a generator's ripple spring for looseness which can improve the reliability of the inspection.

[0002]

2. Description of the Related Art An iron core groove is provided in an iron core of a stator of a generator, and a coil conductor is inserted in this groove. To fix the coil, the coil conductor is formed by using a ripple spring. The structure is such that it is pressed to the bottom of, that is, outward in the radial direction of the stator. At the time of production, even if it is firmly pressed down, it loosens due to aging, so it is necessary to regularly inspect whether it is loose. Conventionally, the inspection of the slackness of the ripple spring that presses the coil in the stator of the generator has relied on a sensory test by a skilled person, in which a person hits with a hammer or the like and hears the sound to judge.

Further, as a tapping sound inspection device for inspecting the state of an object by a tapping sound, for example, there is one disclosed in Japanese Patent Application Laid-Open No. 6-3336 for inspecting peeling of a tile on a wall. In this method, a striking device strikes a wall to which tiles are attached, detects a striking sound generated, converts the striking sound into an electric signal, and extracts a component of a predetermined frequency band related to diagnosis through a bandpass filter. It is checked whether or not the peak value of the extracted signal voltage in the AC state exceeds a predetermined reference value, and if it exceeds, a warning is output to the screen display device.

[0004]

As described above, in the case of human judgment, there is a difference in the diagnostic result depending on the intuition and skill of the measurer. Further, in the conventional hammering sound inspection device, since the frequency of the maximum level of the frequency band in the sound pressure signal generated by striking, that is, the sound pressure of the frequency that is the main component is simply compared, the complex frequency is characterized. In the inspection of the tapping sound, it was not possible to detect the abnormality accurately when the characteristics of the abnormality appeared in frequencies other than the main component.

Further, since the maximum level in the frequency band is targeted for evaluation, it is not possible to distinguish between a sound pressure which is a characteristic of tapping and which has a large instantaneous value and a sound pressure which has a long afterglow and a low level. was there. Because of these
Even if the tapping sound inspection device as described above is applied to the inspection of the looseness of the ripple spring of the generator, it is difficult to accurately detect the looseness.

The present invention has been made to solve the above problems, and an object thereof is to obtain a slack inspection device for a ripple spring of a generator as described below. a. The reliability of the inspection can be improved by comparing the state of vibration generated by the impact with the reference state. b. Prevents the influence of variations in external force applied to the object
Wear. c. If an external force outside the proper range is applied or the input is
You can know that you have exceeded the limit. d. The amplification factor of the amplifier can be easily set to an appropriate value.

[0007]

In order to achieve the above object, in the looseness inspection apparatus for a generator ripple spring according to the present invention, the vibration generated from the ripple spring to which an external force is applied is generated as a vibration signal. And a signal detecting means for detecting the magnitude of the external force as an external force signal.
Output means, conversion means for converting the vibration signal into a time series signal for each of a plurality of predetermined frequency bands, extraction means for extracting the maximum value of the time series signal for each frequency band, and vibration for each frequency band
The reference value setting means for setting the reference value in advance and the external force
Depending on the magnitude, vibration signal, time series signal, maximum value and vibration
Correction means for correcting at least one of the quasi-values,
Each maximum value obtained as a result of correction is used as a vibration reference value or each maximum value.
The vibration reference value obtained as a result of correction of the value or the result of correction
Comparison means for comparing each maximum value thus obtained with a vibration reference value obtained as a result of the correction is provided. Depending on the magnitude of external force
External force in the comparison by the comparison means.
It is possible to prevent the influence of the variation of the height.

Then, the external force signal is applied to a preset external force group.
The ratio calculation means for calculating the ratio divided by the quasi value and the above ratio
A ratio determining means for determining whether or not it is within a predetermined range is provided.
The correction means is based on the above ratio and the vibration signal and the time series signal
And at least one of the maximum value and the vibration reference value are corrected.
It is characterized by having done . Outside by ratio calculation means
Whether the ratio of the force to the external force reference value is within the specified range,
The external force applied to the target object, that is, the excitation force, was too small.
Will be out of this range.
Make sure that you know that you have given an inappropriate external force.

Further, an external force signal amplifying means for amplifying the external force signal and outputting it as an amplified external force signal and a vibration signal amplifying means for amplifying the vibration signal and outputting it as an amplified vibration signal are provided, and the ratio calculating means is provided for amplifying the external force signal. A range over detection means for detecting that the crest value of at least one of the amplified external force signal and the amplified vibration signal exceeds a predetermined value is assumed to be used as the external force signal and the conversion means uses the amplified vibration signal as the vibration signal. It is characterized by being provided. In order to ensure the reliability of the measurement, it is detected that the amplified external force signal or the amplified vibration signal exceeds a predetermined value, that is, that a large signal that saturates the external force signal amplification means or the vibration signal amplification means is input. To do.

Further, it is characterized in that an amplification factor automatic setting means for automatically setting the amplification factor of at least one of the external force signal amplification means and the vibration signal amplification means is provided. The amplification factor can be easily set so that the amplified external force signal and the amplified vibration signal are in an appropriate output range, and the operability is improved. Further, it is possible to prevent the S / N ratio from being lowered and improve the reliability of the inspection.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a configuration diagram of a ripple spring looseness inspection device of a generator, and FIG. 2 is a detailed view of a ripple spring portion. The ripple spring portion is configured, for example, as shown in FIG. In FIG. 2, the ripple spring portion 100 is configured as follows. An iron core groove 102 is formed in the iron core 101 of the stator of the generator, and the coil conductor 10 is formed in the iron core groove 102.
3 are accommodated.

The ripple spring 1 is provided between the spacer 104 and the wedge 106. The wedge 106 is inserted in a wedge groove 107 provided in the iron core 101 from the axial direction of the stator. The coil conductor 103 is pressed against the bottom of the iron core groove 102 by the elastic force of the ripple spring 1. Such a ripple spring 1 loosens due to aging even if it is firmly pressed during manufacturing, so it is necessary to regularly inspect whether it is loose.

Reference numeral 2 indicates that the ripple spring 1 is struck through the wedge 106 (hereinafter, "through the wedge 106" may be omitted, and the ripple spring 1 may be simply struck).
It is a hammer that produces a tapping sound. That is, an external force is applied to the ripple spring 1 via the wedge 106, and the loose state of the ripple spring 1 is determined by a tapping sound. Reference numeral 11 denotes an exciting force sensor which is attached to the hammer 2 and serves as an external force detecting means for converting an exciting force as an external force applied to the ripple spring 1 into an electric signal. Reference numeral 12 is an amplifier that amplifies the electric signal converted by the excitation force sensor 11, and 13 is a rectifier that converts the signal amplified by the amplifier 12 into direct current.

Reference numeral 14 is a peak hold for holding the maximum value of the DC signal output from the rectifier, and 15 is a ratio calculator for obtaining the ratio between the peak hold output and the external force reference value stored in the reference value setting device 16. . A trigger detector 17 detects a trigger from the DC signal output from the rectifier 13.

Reference numeral 19 is a ratio determiner for determining the ratio obtained by the ratio calculator 15. Reference numeral 20 is an automatic range setting device for automatically setting the amplification factor of the amplifier 12 from the maximum value output from the peak hold 14. Reference numeral 21 is a range over detector for detecting a range over from the maximum value output from the peak hold 14.

Reference numeral 3 denotes a microphone which is attached to the hammer 2 and serves as a signal detecting means for converting a tapping sound generated by a struck ripple spring into an electric signal. Reference numeral 4 denotes an amplifier for amplifying the electric signal converted by the microphone 3. 5 is an amplifier 4
It is an analog BPF as a conversion means for separating the signal obtained from the above into each frequency band. This analog BPF5
For example, 9 octaves of 31.25 Hz to 16 kHz are targeted so as to substantially cover the human audible range of 20 Hz to 20 kHz, and a total of 28 bands are provided by giving a resolution of 1/3 octave.

A rectifier 6 rectifies a signal for each frequency band obtained from the analog BPF 5 and converts it into a direct current.
Reference numeral 7 is a peak hold serving as an extraction unit that holds the maximum value of the output from the rectifier 6, and 8 is a corrector that corrects the maximum value output by the peak hold 7 from the ratio obtained from the ratio calculator 15. 9 is the output of the compensator 8 and the reference value setting device 1
The comparator compares the sound pressure reference value as the vibration reference value stored in 0 with a predetermined method, that is, a predetermined comparison reference. Reference numeral 18 is an alarm device that outputs an alarm when it is inspected as an abnormality by inspecting the whole based on the comparison result from each comparator 9.

Reference numeral 31 is a rectifier for converting the signal amplified by the amplifier 4 into direct current. Reference numeral 32 is a peak hold that holds the maximum value of the output from the rectifier 31, and 33 is an automatic range setting device that automatically sets the amplification factor of the amplifier 4 from the maximum value output from the peak hold 32. Reference numeral 34 is a range over detector that detects a range over from the maximum value output from the peak hold 32.

Next, the reference value setting mode for setting the external force reference value and the sound pressure reference value by the object as a reference for the operation, that is, the ripple spring 1 in FIG. 2 which is not loosened will be described. To do. The fact that the ripple spring 1 is not loose is confirmed by, for example, measuring the compression margin of the ripple spring 1.

First, the amplification factors of the amplifier 4 and the amplifier 12 are minimized. In this state, the hammer 2 strikes the ripple spring 1 which is not loosened, the generated impact sound is converted into an electric signal by the microphone 3, and the amplifier 4, the rectifier 31,
The peak hold 7 is used to find the maximum value of the impact sound signal.

This maximum value is input to the automatic range setting device 33 and the gain of the amplifier 4 is set so as to obtain an appropriate measurement range. Similarly, after the vibration generated on the hammer by impact is converted into an electric signal by the excitation force sensor 11, the maximum value of the vibration signal is obtained by the amplifier 12, the rectifier 13 (not passing through the analog BPF 5) and the peak hold 14. This maximum value Is input to the automatic range setting device 20, and the gain of the amplifier 12 is set so as to obtain an appropriate measurement range.

The appropriate measurement range is, for example, the correction by the difference of the exciting force as in this embodiment, and if the range is 1/2 to 2 times, the maximum is 2 compared with the reference value. Since it is necessary to accept double input, the signal level input in this reference value setting mode is 5
The gain is set to be 0%.

In this way, both the vibration and sound amplification factors are set by the first first impact in the reference value setting mode.

Next, a hammer 2 strikes the sound ripple spring 1 as a reference object. At this time, the vibration generated in the hammer 2 is converted into an electric signal by the excitation force sensor 11, and the amplifier 12 gives the gain set by the first impact in the reference value setting mode. The amplified signal is converted into direct current by the rectifier 13. The trigger detector 17 compares the DC signal from the rectifier 13 with a preset reference value, and outputs a trigger when the DC signal exceeds this reference value.

The peak hold 14 records the maximum value of the DC signal input from the rectifier 13. At this time, the operation of the peak hold 14 is started by the trigger signal from the trigger detector 17. Such recording of the maximum value is performed for a certain period of time until the vibration generated by the hammer due to the impact is attenuated to some extent, and thereafter the output from the peak hold 14 is stored in the reference value setting device 16 as the external force reference value.

Similarly, the sound wave generated by striking is converted into an electric signal by the microphone 3, and the amplifier 4 gives the gain set by the first striking in the first reference value setting mode. A plurality of the amplified sound pressure signals are provided and input to the analog BPF 5 which is set to pass different frequency bands, and separated into time series signals for each frequency band.

The time series signals separated for each frequency band by the analog BPF 5 are converted into DC signals by the rectifier 6 and input to the peak hold 7. The maximum value recording operation of the DC signal from the rectifier 6 of the peak hold 7 is performed by the trigger detector 7
Starting with the trigger signal from, the sound pressure attenuation of the object is performed for a certain period of time like the vibration peak hold 14. In this way, the instantaneous maximum value for each frequency band is recorded.

After the end of the fixed time until the sound pressure is attenuated, the maximum value recorded by the peak hold 7 for each frequency band is stored in the reference setter 10 as the sound pressure reference value. By the operation of the reference value setting mode, the reference value setting device 16 stores the external force reference value, which is information indicating the strength of impact,
The reference value setting device 10 stores a sound pressure reference value, which is information indicating an instantaneous maximum sound pressure in each frequency band of tapping.

Next, the inspection mode for inspecting the object will be described. First, the hammer 2 hits the ripple spring 1, which is an object. At this time, as in the reference value setting mode, the vibration generated in the hammer 2 is converted into an electric signal by the excitation force sensor 11, amplified by the amplifier 12, and the rectifier 1 is used.
Converted to DC at 3.

Similarly, the trigger detector 17 also performs trigger output from the DC signal from the rectifier 13, and the peak hold 14
Records the maximum value of the DC signal for a fixed time from the trigger output to the sound pressure attenuation. In the inspection mode, the maximum value recorded in the peak hold 14 is input to the ratio calculator 15 after the end of the fixed time until the hammer vibration is attenuated, and the ratio calculator 15
Is the maximum value from the peak hold 14 and the reference value setting device 1
The ratio with the external force reference value stored in 6 is calculated and output.

Similarly to the reference value setting mode, the sound wave generated by striking is converted into an electric signal by the microphone 3, amplified by the amplifier 4, separated by the analog BPF 5 into a time series signal for each frequency band, and is rectified by the rectifier 6. It is converted into a DC signal and input to the peak hold 7. The peak hold 7 records the maximum value of the DC signal for a fixed time from the trigger output to the sound pressure attenuation.

In the inspection mode, the maximum value recorded by the peak hold 7 is input to the compensator 8 after a certain period of time until the sound pressure is attenuated, and the compensator 8 selects an appropriate value from the ratio obtained from the ratio calculator 15. The correction value is calculated, corrected to the maximum value obtained from the peak hold 7, and output.

At this time, if, for example, the vibration level and the sound pressure are corrected proportionally, when the ratio twice the reference value is obtained by calculation, the maximum value recorded in the peak hold 7 is calculated. Divide by a value of 2. In other words, if the excitation force in the inspection mode is doubled with respect to the excitation force in the reference value setting mode, the sound pressure generated in each frequency band is also doubled. Divide by 2 to convert the value into the excitation force in the reference value setting mode.

The maximum value corrected in this way is compared by the comparator 9 with the sound pressure reference value stored in the reference value setting unit 10 based on a predetermined method or a predetermined comparison standard.
In this embodiment, a comparison result signal is output to the alarm device 18 when the corrected maximum value deviates from a predetermined relationship set in advance.

The predetermined relationship at this time means that, for example, in a certain band, when the corrected maximum value is within the range of 80% to 120% with respect to the sound pressure reference value of that band, it is normal. When it is out of the range, the comparison reference is set so that it is out of the range and a comparison result signal is output. Further, in another band, the comparison result signal is not output, assuming that the range of 70% to 110% is normal with respect to the sound pressure reference value of the band, and the comparison result signal is output when it is out of the range. Set the comparison standard.

Further, when the sound pressure reference value is smaller than the overall sound pressure, the comparison result signal is not erroneously output in the frequency band which is not the main component by taking measures such as releasing the lower limit of the range. To do.

The alarm device 18 inputs the comparison result signal from the comparator 9 in each frequency band, and the determination standard is set so that it is determined to be abnormal when the number of comparison result signals exceeds a preset number, for example, two. When it is determined that there is an abnormality, an alarm is output to the outside.

The ratio inspector 19 outputs an out-of-correction range alarm when the ratio calculated by the ratio calculator 15 exceeds a predetermined relationship. The predetermined relationship at this time is set to, for example, 1/2 to 2 times. Then, when there is an input less than 1/2 or more than twice, an out-of-correction range alarm is output.

When the exciting force changes extremely, the frequency component of the generated sound changes greatly, which makes correction difficult. When the vibration force is extremely weak or extremely strong, as in the case of this ripple spring, a sound unrelated to the looseness of the ripple spring, which is the purpose of inspection, is generated, greatly reducing the reliability of the inspection. Will be made. However, by providing a range limitation for the correction by the excitation force in this way, it is possible to reliably inspect even an object in which the frequency characteristic of the hitting sound generated when the excitation force changes extremely, It is possible to prevent an erroneous inspection due to an extreme change in excitation force.

The correction is performed by correcting the relationship between the waveform analysis result and the sound pressure reference value, that is, the sound pressure reference value stored in the reference value setting unit 10 of the comparator 9 according to the magnitude of the vibration signal. The output of the amplifier 12 and each analog B
One or more of the output of the PF 5, the output of the rectifier 6, or the sound pressure reference value stored in the reference value setting device 10 may be corrected.

When the magnitude of vibration detected by the exciting force sensor 11 exceeds a predetermined value, the peak hold 1
4. Since the peak hold 7 as the extraction means is provided with the trigger detector 17 for instructing the start of the operation, it is possible to reduce the influence of noise from the surroundings and improve the reliability of the inspection.

Although the trigger signal of the trigger detector 17 is given to the peak hold 7, the microphone 3, the amplifier 4, the analog BPF 5 as the converting means, the rectifier 6, the corrector 8 as the correcting means, and the comparing means. The same effect can be obtained even if the storage operation of the maximum value is started or the comparison operation is started by giving the same to the comparator 9 or the like.

In each of the reference value setting mode and the inspection mode, the range over detector 21 inputs the maximum value obtained from the peak hold 14 for the vibration signal, and when the maximum value exceeds a predetermined relationship, the range over is detected. Output an alarm. The range over detector 34 inputs the maximum value obtained from the peak hold 7 for a sound signal, and outputs a range over alarm when the measurement signal exceeds a predetermined relationship.

The predetermined relationship at this time is set, for example, as 99% of the measurement range. In this case, when a signal exceeding 99% is input, a range over alarm is output.

Further, by setting an appropriate measurement range at the first first impact in the reference value setting mode, the trouble of manually setting the measurement range is eliminated and the operability is improved. Furthermore, when setting manually, if the range is not appropriate, the S / N ratio will decrease and the reliability of the inspection will decrease, but this will not occur because the range is automatically set. Therefore, it is possible to obtain a hammering sound inspection device with improved inspection reliability.

Further, by outputting the range over alarm immediately before the input of each signal is saturated, it is possible to prevent the erroneous determination due to the saturation of the amplifier and to obtain the tapping sound inspection device with improved inspection reliability. Becomes Note that the inspection can be performed at high speed by using the analog BPF.

Embodiment 2. FIG. 3 is a configuration diagram of a ripple spring looseness inspection device for a generator according to another embodiment of the present invention. In FIG. 3, the following points are different from those shown in FIG. 1, but other configurations are the same as those shown in FIG. The maximum value of the sound pressure extracted by the peak hold 7 for each frequency band is corrected by the corrector 8 and then input to the reference setting device 10, and the reference setting device 10 outputs the maximum value of the input maximum value. The difference is that an average value is obtained for each frequency band and used as a sound pressure reference value, and a range of variation of the maximum value is obtained and a comparison reference is determined based on the range.

Prior to work, clean the sound of the ripple spring 1 to 5
Select 0 places. The soundness of the ripple spring 1 is confirmed by measuring the compression margin of the ripple spring 1. In addition, "healthy"
Strictly speaking, it means that the ripple spring 1 is slightly loosened during use of the generator due to withering of an insulator, etc., but the looseness is within an allowable range.

Next, the operation will be described. First, a given arbitrary ripple spring 1 is hit with a hammer 2. At this time, the vibration generated in the hammer 2 is detected as an external force applied to the ripple spring 1 by the excitation force sensor 11, converted into an electric signal, and the peak hold 14 extracts the maximum value. The maximum value extracted by the peak hold 14 is the standard setting device 16
Is stored as the external force reference value. At this time, the ratio calculator 1
5 outputs the ratio 1. These are the same as those shown in the embodiment of FIG.

On the other hand, the maximum value of the sound pressure signal extracted by the peak hold 7 passes through the corrector 8 as it is and is input to the reference setting device 10 because the ratio output from the ratio calculator 15 is 1. It is stored as a pressure reference value.

Next, the variation of the sound pressure reference value is obtained. Fifty healthy ripple springs are hit to obtain 50 data. The maximum value of the sound pressure obtained for each hit, that is, the maximum value for each frequency band extracted by the peak hold 7, is
The corrector 8 corrects the ratio calculated by the ratio calculator 15 each time, and the corrected value is stored in the reference value setting device 10. That is, if the ratio is 1.2, it is assumed that the external force applied this time is 1.2 times the external force when the external force reference value was stored in the reference setter 16 first, and divided by 1.2. Normalize.
In this way, 50 pieces of data are obtained for each frequency band.

Then, the average value is obtained and used as the sound pressure reference value. Further, the range of variation of the maximum value is obtained for each frequency band. For example, in the frequency band number A1, the sound pressure reference value is set to 100 and 95 to 110, and in the frequency band number A2, from 90 to 105, the range of variation is obtained for all 28 bands. Then, the comparator 9 does not output the comparison result signal if it is within the range of variation determined as described above, and if it exceeds this, the comparison reference is determined so that the comparison result signal is output to the alarm device 18. Also,
If it is expected that there may be cases where the variation of normal data obtained in the reference value setting mode is exceeded, a margin of about ± 10% may be provided to prevent erroneous determination.

In the alarm device 18, even if the alarm device is normal, there is a possibility that it may overflow from the data obtained from the above-mentioned 50 ripple springs. Therefore, even if only one comparison result signal is issued, it is not inspected as abnormal, When 3 or more are inspected as abnormal, a judgment standard is set so that an alarm is issued.

As described above, the range of the maximum value of the time series signal for each frequency band of the sound pressure signal is found from a sufficient number of data by hitting the sound ripple spring, and the comparison is made based on this range. If the ripple spring is loosened by a predetermined value or more, an abnormality appears somewhere in the frequency band and the protrusion exceeds the comparison reference, so that the defect can be surely detected.

The following is also possible. 100 ripple springs 1 whose soundness is not completely secured but sound sound are selected, and 100
Take data. If there is data that exceeds three times the standard deviation σ, it is determined that the looseness is equal to or greater than the allowable value, and this data is excluded to obtain the average value and the range of variation. By doing so, even if the ripple spring has a large degree of looseness, it can be prevented from incorporating it into the sound pressure reference value or the comparison reference.

The data obtained by hitting the ripple spring 1 at the time of new product, that is, the compression allowance of the ripple spring within a predetermined range, for example, within that range when it is allowed up to plus or minus 10% of the reference value When the data of the range of variation of the sound pressure reference value and the maximum value when the ripple spring is hit is stored, the data can be used. In addition, the comparison standard set by each method as described above can be further corrected and learned by the data obtained in the subsequent actual inspection.

Third Embodiment Although the analog BPF is used to obtain the maximum value for each frequency band in the first embodiment, a digital BPF may be used. In this embodiment, a case where a digital BPF is used will be described based on the configuration diagram of FIG. In FIG. 4, 51 is an A / D converter that converts the analog signal from the rectifier 13 into a digital signal, and 52 is an A / D converter that converts the analog signal from the amplifier 4 into a digital signal. Reference numeral 53 is a maximum value calculator for calculating the maximum value of the output of the A / D converter 51.

Reference numeral 61 is a digital BPF as conversion means for converting a digital signal into a time series signal for each frequency band. The digital BPF 61 has a frequency range of 31.25 to 16,000 Hz so as to substantially cover the human audible range of 20 to 20,000 Hz as in the embodiment of FIG.
A total of 28 bands are provided by targeting the octave and providing resolution for each 1/3 octave. Reference numeral 62 is a rectifier for rectifying the AC signal from the digital BPF, and 63 is a maximum value calculator as an extracting means for extracting the maximum value from the rectified digital signal.

Reference numeral 64 denotes a corrector, which corrects the maximum value output by the maximum value calculator 63 based on the ratio obtained from the ratio calculator 15 and outputs a correction value. Reference numeral 65 denotes a comparator, which compares the output of the corrector 64 with the sound pressure reference value stored in the reference value setting device 66 by a predetermined method. The rectifier 62, the peak hold circuit 63, the corrector 64, the comparator 65, and the reference value setter 66 are digital BPs provided for all 28 bands.
28 pieces are provided corresponding to each F61.

A maximum value calculator 41 extracts the maximum value from the digital signal from the A / D converter 52 rectified by the rectifier 31. Since other configurations are the same as those shown in FIG. 1, corresponding components are designated by the same reference numerals and description thereof will be omitted.

Next, the operation will be described. First, a reference value setting mode for setting each reference value using a reference object will be described. The A / D converter 51 converts the analog DC signal from the rectifier 13 into a digital signal. At this time, the A / D converter 51 receives the trigger signal from the trigger detector 17, starts its operation, and continues for a certain period of time until the vibration generated by the hammer due to the impact is attenuated to a predetermined value or less. The maximum value calculator 53 extracts the maximum value of the digital signal from the A / D converter 51, and this maximum value is stored in the reference value setter 16 as the external force reference value.

Similarly, the sound wave generated by striking is converted into an electric signal by the microphone 3, given an appropriate gain by the amplifier 4, and then converted into a digital signal by the A / D converter 52. At this time, the A / D converter 52 starts its operation in response to the trigger signal from the trigger detector 17, and operates for a certain period of time until the sound pressure generated by the impact of the object is attenuated to a predetermined value or less. This converted digital signal is
The signals are input to 28 digital BPFs 61 set to pass different frequency bands, and separated into time series signals for each frequency band.

The time series signals separated for each frequency band by the digital BPF 61 are converted into DC signals by the rectifier 62 and input to the maximum value calculator 63. Maximum value calculator 63
Extracts the maximum value of this DC signal and outputs the reference value setter 66.
To store. In this way, the instantaneous maximum value for each frequency band is extracted, and the reference value setter 66 is used as the sound pressure reference value.
Stored in.

By the operation of the reference value setting mode as described above, the reference value setting device 16 stores the external force reference value which is information indicating the strength of the impact, and the reference value setting device 66 stores each frequency band of the tapping sound. A sound pressure reference value, which is information indicating the instantaneous maximum sound pressure at, is stored.

Next, the inspection mode for inspecting the object will be described. First, the hammer 2 hits the ripple spring 1, which is an object. At this time, as in the reference value setting mode, the vibration generated in the hammer 2 is converted into an electric signal by the excitation force sensor 11, amplified by the amplifier 12, and the rectifier 1 is used.
Convert to DC at 3. Similarly, the trigger detector 17 also outputs a trigger signal from the DC signal from the rectifier 13, and the A / D converter 51 converts the DC signal into a digital signal for a fixed time from trigger output to sound pressure attenuation. The maximum value calculator 53 extracts and outputs the maximum value of the digital signal.

In the inspection mode, the maximum value extracted by the maximum value calculator 53 is input to the ratio calculator 15, which calculates the maximum value and the external force reference value stored in the reference value setting device 16. And the ratio is calculated and output.

Similarly to the reference value setting mode, the sound wave generated by striking is converted into an electric signal by the microphone 3, amplified by the amplifier 4, and converted into a digital signal by the A / D converter 52. At this time, the operation of the A / D converter 52 is started by the trigger signal from the trigger detector 17, and is performed for a fixed time until the sound pressure is attenuated. The digital signal is separated into time series signals for each frequency band by the digital BPF 61, converted into a DC signal by the rectifier 62, and input to the maximum value calculator 63. The maximum value calculator 63 extracts and outputs the maximum value of the DC signal.

In the inspection mode, the maximum value extracted by the maximum value calculator 63 is input to the corrector 64 and the corrector 6
4 calculates an appropriate correction value based on the ratio obtained from the ratio calculator 15, corrects the maximum value obtained from the maximum value calculator 63, and outputs it.

The corrected maximum value is compared by the comparator 65 with the sound pressure reference value stored in the reference value setting unit 66, and when the preset value is out of the predetermined relationship, the comparison result signal is output by the alarm unit 18. Is output to. The predetermined relationship to set is
Similar to the embodiment shown in FIG. 1, in a certain band, for example, when the corrected maximum value is within the range of 80% to 120% with respect to the sound pressure reference value of the band, the comparison result signal is regarded as normal. When the value is out of this range, that is, when it is less than 80% and more than 120%, it is set as abnormal and the comparison result signal is output. Also other,
In a certain band, when the sound pressure reference value of the band is out of the range of 70% to 110%, the comparison result signal is output as being out of the range.

When the sound pressure reference value is smaller than the overall sound pressure, the comparison result signal is not erroneously output in the frequency band which is not the main component by taking measures such as canceling the comparison on the lower limit side. To When the number of the input comparison result signals exceeds a preset number, for example, two, the alarm device 18 sounds a buzzer as a notification and blinks a lamp to give an alarm.

As described above, by using the digital BPF 61 as a method for obtaining a time-series signal for each frequency band, the device can be downsized, and the frequency band for changing or diagnosing the filter characteristics because of processing by software (S / W). It is possible to flexibly deal with the addition of.

Fourth Embodiment FIG. 5 is a configuration diagram of a ripple spring looseness inspection device for a power generator according to another embodiment of the present invention. In the embodiment of FIG. 4, in order to obtain the maximum value for each frequency band,
Although the digital BPF was used, the wavelet transform (Wa
Velet Transform) may be used. Hereinafter, the case where the wavelet transform is used will be described based on the configuration diagram of FIG.

In this embodiment, a wavelet transform calculator 71 is provided so as to obtain a time series signal for each frequency band. Other operations are as shown in FIG.
This is the same as the embodiment. Since the effective value of the wavelet transform is calculated by the analytical calculation, it is not necessary to provide a rectifying means.

In the figure, reference numeral 71 denotes a wavelet transform as a transforming means.
m) An arithmetic unit, a basis function (mother wavelet)
Is expanded or reduced to separate the digital sound pressure signal into time-series signals for each frequency band. The wavelet-transformed signals are input to the maximum value calculator 63, the corrector 64, and the comparator 65 provided in 28 sets.

The comparator 65 is compared with the sound pressure reference value stored in the reference value setting unit 66 as in the case shown in FIGS. 1 and 4, and when the preset relationship is established, The comparison result signal is output to the alarm device 18.

At this time, by selecting an appropriate basis function according to the measured waveform and the phenomenon to be observed, the frequency separation characteristic is improved and the reliability of the inspection can be improved. Further, the apparatus can be downsized by using the wavelet transform calculator.

Embodiment 5. FIG. 6 is a block diagram of a ripple spring looseness inspection device for a generator according to another embodiment of the present invention. In the embodiment of FIG. 4, in order to obtain the maximum value for each frequency band,
Although the digital BPF is used, a short time FFT may be used. Hereinafter, the case of using the short-time FFT will be described with reference to FIG. In this embodiment, the short time F
An FT calculator 81 is provided to obtain a time series signal for each frequency band.

Other operations are similar to those of the embodiment shown in FIG. Since the short-time FFT calculates the effective value by its analytical calculation, it is not necessary to provide a rectifying means. In FIG. 6, 81 is a short time F as a conversion means.
FT (STFT: Short-Time Fourier)
r-Transform) calculator, which is adapted to obtain a time-series signal for each frequency band.

Thus, the short time F which is the Fourier transformer
The frequency resolution can be improved by providing the FT calculator 81 and determining the time series signal for each frequency band.

Therefore, by utilizing the excellent resolution of the short-time FFT, the reliability of diagnosis can be improved when the characteristic of the change in frequency appears due to the configuration of the ripple spring. Further, the device can be downsized by using the FFT calculator for a short time.

In each of the above embodiments, the hammer is used to apply the external force, but the external force may be applied by other means, for example, the electromagnetic force or the cylinder may be used to apply the exciting force.

In each of the above embodiments, the external force is detected by the excitation force sensor 11 and the impact sound is detected by the microphone 3. However, a vibration detector is used instead of the microphone for impact sound. Good. In each of the above-mentioned embodiments, those of audible frequencies are called sounds and those of a wider frequency range are called vibrations. However, in the present invention, the inspection device is not limited to sounds, but sounds and vibrations. No distinction is made, and the one due to vibration is included.

Although the alarm device 18 gives an alarm, the signals and the calculated values in such an inspection, for example, the sound pressure reference values stored in the setting device 10 in the embodiment of FIG. And a normal or abnormal range set as a reference for comparison set in the comparator 9, a correction value calculated by the ratio calculator 15, a corrected maximum value from each corrector 8 in the inspection, and the like in the form of dots or bands. It is also possible to improve the operability by making it easy to confirm by displaying the color on the CRT and coloring the color out of the range with red or the like.

The maximum value corrected by the corrector 8 can also be shown in the normal range so as to be visually recognized. At this time, if the comparison result deviates from the predetermined relationship, the maximum value detected at that time may be displayed in red.

Further, by inserting a small inspection robot equipped with the looseness inspection device of the present invention into the air gap between the rotor and the stator of the generator, the rotor withdrawal work during the periodic inspection can be simplified.

Further, instead of the sound pressure reference value and the comparison reference shown in the third to fifth embodiments, the sound pressure reference value and the comparison reference obtained by the same defining method as those shown in the second embodiment are used. You can also

[0087]

Since the present invention is constructed as described above, it has the following effects.

A signal detecting means for detecting the vibration generated from the ripple spring to which an external force is applied as a vibration signal, and an external force.
Of external force signal as an external force signal, conversion means for converting a vibration signal into a time series signal for each of a plurality of predetermined frequency bands, and extraction means for extracting the maximum value of the time series signal for each frequency band And the vibration reference value for each frequency band
Depending on the magnitude of external force and the reference value setting means to set
Of vibration signal, time series signal, maximum value and vibration reference value
Correction means for correcting at least one of the
Each maximum value obtained is used as a vibration reference value or each maximum value is corrected.
Resulting vibration reference value or each maximum obtained as a result of correction
Since the comparison means for comparing the value with the vibration reference value obtained as a result of the correction is provided, by correcting according to the magnitude of the external force, the influence of the variation in the magnitude of the external force in the comparison by the comparison means. It is possible to prevent the receiving and to improve the reliability of comparison.

Then, the external force signal is applied to a preset external force group.
The ratio calculation means for calculating the ratio divided by the quasi value and the above ratio
A ratio determining means for determining whether or not it is within a predetermined range is provided.
The correction means is based on the above ratio and the vibration signal and the time series signal
And at least one of the maximum value and the vibration reference value are corrected.
Since it is characterized in that the improper external force that is out of the predetermined range is given, the reliability of comparison can be improved.

Further, external force signal amplifying means for amplifying the external force signal and outputting it as an amplified external force signal and vibration signal amplifying means for amplifying the vibration signal and outputting it as an amplified vibration signal are provided, and the ratio calculating means is provided for amplifying the external force signal. A range over detection means for detecting that the crest value of at least one of the amplified external force signal and the amplified vibration signal exceeds a predetermined value is assumed to be used as the external force signal and the conversion means uses the amplified vibration signal as the vibration signal. Since it is provided, it is detected that the amplified external force signal or the amplified vibration signal exceeds a predetermined value, that is, a large signal that saturates the external force signal amplification means or the vibration signal amplification means is detected. Therefore, the reliability of the inspection can be secured.

Further, since the amplification factor automatic setting means for automatically setting the amplification factor of at least one of the external force signal amplification means and the vibration signal amplification means is provided, the amplified external force signal and the amplified vibration signal are The amplification factor can be easily set to obtain an appropriate output range, and operability is improved.
Further, it is possible to prevent the S / N ratio from being lowered and improve the reliability of the inspection.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a ripple spring looseness inspection device for a generator according to an embodiment of the present invention.

FIG. 2 is a detailed view of a ripple spring portion of the generator.

FIG. 3 is a configuration diagram of a ripple spring looseness inspection device for a generator according to another embodiment of the present invention.

FIG. 4 is a configuration diagram of a ripple spring looseness inspection device for a power generator according to another embodiment of the present invention.

FIG. 5 is a configuration diagram of a ripple spring looseness inspection device for a generator according to another embodiment of the present invention.

FIG. 6 is a configuration diagram of a ripple spring looseness inspection device for a generator according to another embodiment of the present invention.

[Explanation of symbols]

1 ripple spring, 2 hammer, 3 microphone, 4
Amplifier, 5 analog BPF, 6 rectifier, 7 peak hold circuit, 8 corrector, 9 comparator, 10 reference value setting device, 11 excitation force sensor, 12 amplifier, 13
Rectifier, 14 peak hold, 15 ratio calculator, 1
6 Reference value setting device, 17 Trigger detector, 18 Alarm device, 19 Ratio judging device, 20 Range automatic setting device, 21
Range over detector, 31 rectifier, 32 peak hold, 33 range automatic setting device, 34 range over detector, 41 maximum value calculator, 51, 52 A / D converter, 53 maximum value calculator, 61 digital BPF, 62
Rectifier, 63 maximum value calculator, 64 corrector, 65
Comparator, 66 Reference value setting device, 71 Wavelet transform calculator, 81 Short time FFT calculator.

Continuation of the front page (56) Reference JP-A-9-113351 (JP, A) JP-A-2-130429 (JP, A) JP-A-8-177530 (JP, A) JP-A-10-274558 (JP , A) JP-A-10-82714 (JP, A) JP-A-6-331468 (JP, A) JP-A-60-207013 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) G01M 19/00 G01M 7/08

Claims (4)

(57) [Claims] 1. A signal detecting means for detecting a vibration generated from a ripple spring applied with an external force as a vibration signal, and an external force detecting means for detecting the magnitude of the external force as an external force signal.
When a conversion means for converting the vibration signal into a time series signal for each of the plurality of predetermined frequency band, and extracting means for extracting the maximum value of the time series signals for each of the frequency band, the frequency band
Reference value setting means for setting the vibration reference value for each region in advance
And the vibration signal and the time system according to the magnitude of the external force.
Less of column signal, maximum value and vibration reference value
And a correction means for correcting one of them, and a result of the above correction.
The above-mentioned maximum values and the above-mentioned vibration reference values or the above-mentioned maximum values
The vibration reference value obtained as a result of the correction or the correction
The above maximum values obtained as a result of
A looseness inspection device for a ripple spring of a generator, comprising: a comparison means for comparing the vibration reference value . 2. An external force signal is set to a preset external force reference value.
The ratio calculation means for obtaining the ratio divided by
A ratio determining means for determining whether or not the
Positive means based on the above ratio, vibration signal and time series signal and maximum
At least one of the value and the vibration reference value is corrected.
The looseness inspection device for the ripple spring of the generator according to claim 1, wherein 3. An external force signal is amplified to obtain an amplified external force signal.
External force signal amplifying means to output and amplify vibration signal by amplifying vibration signal
Providing a vibration signal amplification means for outputting as a motion signal,
The calculation means uses the amplified external force signal as the external force signal.
However, the conversion means uses the amplified vibration signal as the vibration signal.
And at least one of the amplified external force signal and the amplified vibration signal.
Range-o that detects when the peak value of
The looseness inspection device for the ripple spring of the generator according to claim 2, further comprising a bar detecting means . 4. External force signal amplifying means and vibration signal amplifying means
Of at least one of the
The looseness inspection device for the ripple spring of the generator according to claim 3, further comprising a motion setting means .