JPH0949253A - Diagnostic device for excavator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quantitatively grasp conditions of an excavator to accurately diagnose abnormalities of the excavator. SOLUTION: Detection signals from a sound wave sensor 24 are amplified by amplifiers 26, 27 and components of each band are extracted by narrow-band filters 28a-28n and a wide-band filter 30 and the components are detected by detectors 29a-29n, 31. An amplitude ratio calculating means 232 receives detected signals from the detectors 29a-29n, 31 to determine average amplitude of the detected signals and thereafter amplitude ratio for the detected signals from the detector 31 is determined for each of the detected signals from the detectors 29a-29n. A distribution obtaining means 234 determines frequency distribution of amplitude ratio for each signal from the amplitude ratio and a statistical quantity calculation means 236 calculates mean values and variances of each signal based on the frequency distributions. An abnormality judging means 238 diagnoses abnormalities of the excavator based on the mean values and variance and display the results on a displayer 33.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a machine for digging a machine such as a shield machine or a tunnel boring machine for diagnosing a malfunction of the machine while it is in operation.

[0002]

2. Description of the Related Art Conventionally, as a method of diagnosing an abnormality due to a failure of a machine during operation, earth pressure in a cutter chamber of a shield machine, a rotating torque of a cutter head, a propulsive force of a shield jack, and earth discharging are used. When the rotation torque of the screw conveyor is detected by each sensor, and the detected value is above or below the set value,
A method has been adopted in which it is determined that an abnormality has occurred in a movable part such as a cutter head, a shield jack, or a screw conveyor.

[0003]

However, according to this method, it is not possible to detect an abnormality caused by wear or damage of a mechanical part or the like that gradually occurs when the excavator is operated for a long time. For example, if it is measured that the rotation torque of the cutter head has exceeded the set value, the cause is the wear of the cutter tip, or the entry of earth and sand into the bearing of the cutter head drive shaft. Alternatively, it is difficult to accurately determine whether the cutter head is due to excavating the rock formation by simply monitoring the monitor in the ground control room.

Also, regarding the life of the cutter tip attached to the cutter head, the wear limit of the cutter tip has hitherto been determined from the distance the cutter tip is transferred on the outermost periphery of the shield machine and the rock quality of the ground to be excavated. The excavation extension distance to reach was calculated and life was estimated. However, the actual amount of wear did not match the calculated value due to changes in operating method and ground,
Accurate judgment is difficult.

The present invention has been made under such circumstances, and an object thereof is to detect the state of the excavator quantitatively by statistical analysis of the detection result by the sound wave sensor and detect the abnormality of the excavator. And to provide a diagnostic device for a machine to accurately diagnose the life of a cutter chip.

[0006]

In order to achieve the above object, the present invention achieves the above object by amplifying a sound wave sensor for detecting sound or vibration generated during the operation of a machine and amplifying an output signal of the sound wave sensor to a predetermined level. From the output signal of the amplifier, a plurality of narrow band filters for extracting signals in a plurality of narrow bands having different center frequencies, and from the output signal of the amplifier, within a predetermined band including abnormal sound or abnormal vibration. A wideband filter for extracting a signal and the amplitudes of the output signals of the narrowband filter and the wideband filter for each predetermined time are obtained, and the amplitude ratio of each output signal of the narrowband filter to the output signal of the wideband filter is calculated. An amplitude ratio calculation means, a distribution acquisition means for obtaining a frequency distribution of the amplitude ratio of each output signal of the narrow band filter within a fixed period, An abnormality occurs in the excavator based on the statistical quantity calculating means for obtaining a numerical value representing the characteristic of the frequency distribution obtained by the distribution acquiring means and the numerical value representing the characteristic of the frequency distribution obtained by the statistical quantity calculating means. And an abnormality determining means for determining whether or not the determination is made.

According to the present invention, at least the average value, the maximum value, the minimum value, the median value, and the mode value of the amplitude ratio is represented in the numerical value representing the characteristic of the frequency distribution as a representative value of the amplitude ratio. It is characterized in that one is included. The present invention also provides
In the numerical value representing the characteristic of the frequency distribution, as the dispersion of the amplitude ratio, the variance of the amplitude ratio, the standard deviation, the average deviation,
At least one of the slopes of the curve representing the frequency distribution is included. The present invention is also characterized in that the abnormality determining means determines that an abnormality has occurred in the excavator when the representative value satisfies a predetermined condition.
The present invention is also characterized in that the abnormality determination means determines that an abnormality has occurred in the excavator when the dispersion degree satisfies a predetermined condition. The present invention is also characterized by further comprising display means for displaying the determination result by the abnormality determination means. The present invention also provides that the sound wave sensor comprises
It is characterized in that it is provided on a partition wall of the cutter chamber of the excavator.

The sound wave sensor detects sound or vibration generated during the operation of the machine, and the amplifier amplifies the output signal of the sound wave sensor to a predetermined level. Then, the plurality of narrow band filters extract signals within narrow bands having different center frequencies from the output signal of the amplifier, respectively, while the wide band filter within the predetermined band including abnormal sound or abnormal vibration from the output signal of the amplifier. The signal of is extracted. The amplitude ratio calculating means obtains the amplitudes of the output signals of the narrow band filter and the wide band filter for each predetermined time, and outputs the respective output signals of the narrow band filter,
The amplitude ratio of the output signal of the wide band filter is calculated.
The distribution acquisition means obtains a frequency distribution within a fixed period of the amplitude ratio of each output signal of the narrow band filter calculated by the amplitude ratio calculation means, and the statistic calculation means calculates the frequency distribution calculated by the distribution acquisition means. Find the numerical value that represents the characteristics of. Then, the abnormality determining means determines whether or not an abnormality has occurred in the excavator based on the numerical value representing the characteristic of the frequency distribution obtained by the statistic calculating means.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described. FIG. 1 is a block diagram showing an example of a diagnosis device for an excavator according to the present invention, FIG. 2 is a schematic configuration diagram showing an entire earth pressure type shield excavator equipped with the diagnostic device shown in FIG. 1, and FIG. 3 is a shield excavation device shown in FIG. It is a detailed block diagram which shows a machine in detail.

2 and 3, reference numeral 10 denotes a shield machine, which includes a shield frame 11, a cutter head 12 for excavating the ground by rotating at the front end of the shield frame 11 in the direction of excavation, and a partition wall behind the cutter head 12. A cutter chamber 14 formed by 13 for retaining the excavated soil excavated by the cutter head 12 in a filled state, a screw conveyor 15 for continuously discharging the excavated soil in the cutter chamber 14, and a hydraulic jack for propulsion (not shown). And an erector for assembling the segment 16 and the like. The drive shaft 12a of the cutter head 12 is a partition wall 13
Is rotatably supported by a hydraulic motor 1 via a bearing 17.
It is driven to rotate by 8. Reference numeral 19 is a ventilation device.

In FIG. 2, reference numeral 20 is a control room provided on the ground, and the shield machine 1 is installed in the control room 20.
An operation panel 21 for operating 0 is installed, and a computer 22 for controlling the shield machine 10 is also installed. Further, in the control room 20, a diagnostic device main body 23a of the excavator according to the present invention is installed, and in the diagnostic device main body 23a, a sound wave sensor 24 attached to the partition wall 13 is installed.
Are connected via a signal cable 25.

The sound wave sensor 24 is used for excavating sound and vibration of the ground propagating from the cutter head 12 to the partition wall 13 and the drive shaft 12a.
The sound sensor 24 detects an abnormal sound generated in a mechanical portion such as the bearing 17 or the bearing 17. As the sound wave sensor 24, an acceleration sensor made of PZT ceramics or the like can be used. The frequency characteristic is audible sound band (10Hz-20K
It may be flat in Hz).

Next, the configuration of the diagnostic device 23 will be described in detail with reference to FIG. In FIG. 1, the sound wave sensor 2
A preamplifier 26 for amplifying the detection signal is connected to 4, and the preamplifier 26 is connected to the diagnostic apparatus main body 23 a via a signal cable 25.

The diagnostic apparatus main body 23a includes a signal processing section 23b.
And an analysis / diagnosis unit 23c and a display device 33. First, the signal processing unit 23b includes the variable amplifier 2
7, narrow band filters 28a to 28n, detectors 29a to 29
9n, broadband filter 30, detector 31, and AG
It is composed of a C circuit 32. The variable amplifier 27 is
It is an amplifier whose amplification degree changes according to the signal from the AGC circuit 32.
The detection signal is received via the control unit and continuously controlled so that the time average value of the amplitude level becomes substantially constant. The plurality of narrow band filters 28a to 28n are connected to the variable amplifier 2
Narrow-band signals having different center frequencies set for each abnormal sound of the excavator 10 are extracted from the signal output from 7 and output as detection signals 28as to 28ns of each band. The plurality of detectors 29a to 29n individually detect the detection signals 28as to 28ns of the respective bands output from the narrow band filters 28a to 28n. On the other hand, the broadband filter 30 has a predetermined bandwidth (200 Hz to 10 KH) including various abnormal sounds from the signal output from the variable amplifier 27.
z) signal is extracted, and the detector 31 uses the broadband filter 3
The signal output from 0 is detected. In addition, the AGC circuit 3
2 controls the amplification degree of the variable amplifier 27 based on the amplitude level of the detection signal output from the detector 31. The center frequencies of the narrow band filters 28a to 28n are determined from experimentally obtained frequencies of various abnormal sounds caused by wear of the cutter chip, damage of mechanical parts such as bearings, and the like.

The analysis / diagnosis unit 23c has an amplitude ratio calculating means 23.
2, a distribution acquisition unit 234, a statistic calculation unit 236, and an abnormality determination unit 238. The amplitude ratio calculation means 232 first detects each of the detectors 29a to 29n,
The output signal of 31, that is, the detection signal is sampled at a cycle of several msec, specifically, at a cycle of 4 msec in the present embodiment, is converted into a digital signal, and for each detection signal,
In the present embodiment, the average value of the five sampled signals is obtained, and these are used as the amplitude of each detected signal. Next, the amplitude of the detected signal from each of the detectors 29a to 29n thus obtained is divided by the amplitude of the detected signal from the detector 31, and the detected signal of each of the detectors 29a to 29n is detected by the detector 31. The amplitude ratio for the detected signal is calculated. As described above, in the present embodiment, the sampling is performed at a cycle of 4 msec and the average value of the five signals is obtained.
Will calculate the amplitude ratio every 20 msec.

The distribution acquisition means 234 calculates the amplitude ratio calculation means 232 every few minutes, specifically, every two minutes in this embodiment, and within the time of several minutes (two minutes in this embodiment). The amplitude ratio of each detection signal, and accordingly the detection signals 28as ...
The frequency distribution of the amplitude ratio of 28 ns is obtained. That is, the distribution acquisition unit 234 divides the amplitude ratio into a plurality of levels (20 levels in this embodiment) at a predetermined increment (0.05 in this embodiment) for each detection signal 28as to 28ns, and for each level. Calculate the number of occurrences of the amplitude ratio of.

The statistic calculation means 236 is the distribution acquisition means 2
Based on the frequency distribution obtained by 34, each detection signal 28as
In this embodiment, the average value and the variance are obtained as the numerical values representing the representative value of the amplitude ratio and the dispersion degree, every 28 ns. Then, the statistic calculating means 236 supplies the obtained average value and variance to the abnormality determining means 238, and outputs signals representing the average value and variance to the display device 33 to display them. The abnormality determining means 238 determines whether or not there is an abnormality in the machine 10 based on the average value and the variance of the amplitude ratios obtained by the statistic calculating means 236, and a signal indicating the determination result is displayed on the display device 33. Output. The amplitude ratio calculation means 232, the distribution acquisition means 234,
Statistical amount calculation means 236 and abnormality determination means 238
Can be configured by, for example, a personal computer including an A / D converter.

Next, the operation of the diagnostic apparatus for the excavator constructed as above will be described. While the shield machine 10 is operating, ground excavation sound and crushing sound by the cutter head 12, vibration of the machine body, rotation sound of the cutter drive shaft 12a, and other sound and vibration in the audible range are detected by the sound wave sensor 2.
After being picked up by 4 and converted into an electric signal,
The signal is amplified by the preamplifier 26 and input as a detection signal to the variable amplifier 27 through the signal cable 25. The detection signal amplified by the variable amplifier 27 is the wide band filter 30.
When added to the bandpass filter 30, the excavator 1
It cuts signals in the high frequency range of 10 KHz or more and the low frequency range of 200 Hz or less generated from the hydraulic system of 0, the ventilation device 19 in the tunnel, etc.
Pass signals with frequencies in the range 0 Hz to 10 KHz. FIG. 6 is a graph showing the frequency characteristic of the wide band filter 30.

The signal that has passed through the wide band filter 30 is detected by the wave detector 31 and is output to the AGC circuit 32 as a waveform as shown in FIG. A receiving this detection output
In the GC circuit 32, the AG based on the time average of the amplitude is used.
By performing C processing and feeding back the obtained AGC signal to the variable amplifier 27, the amplification degree is changed according to the type of excavator, operating conditions, soil properties of the excavated ground, etc. so that the output amplitude becomes almost constant. To control.

On the other hand, when the detection signal amplified by the variable amplifier 27 is added to each of the narrow band filters 28a to 28n,
Since each of the narrow band filters 28a to 28n is a narrow band pass filter having a bandwidth of about 1/10 of the center frequency above and below the different center frequency, only the detection signal of the frequency that matches each narrow band is detected. Corresponding wave detectors 29a-2 are passed through the corresponding narrow band filters 28a-28n.
It is output to 9n. FIG. 4 shows the frequency characteristic of the narrow band filter 28a, and FIG. 5 shows the frequency identification of the narrow band filter 28b.

Each of the detectors 29a to 29n has a detection signal 28as which has passed through the corresponding narrow band filter 28a to 28n.
.About.28 ns are detected respectively, and the result is amplitude ratio calculation means 2
32.

The amplitude ratio calculation means 232 is provided for each of the detectors 29a ...
When the detection signals are received from 29n and 31, first, the detection signals are sampled at a constant cycle of 4 msec in the present embodiment and converted into digital signals. For each detection signal, the average of the five signals sampled in the present embodiment is calculated. The values are calculated and used as the amplitude of each detection signal. Next, the above-mentioned amplitude of the detection signal from each of the detectors 29a to 29n thus obtained is divided by the above-mentioned amplitude of the detection signal from the detector 31 to detect the detection signal of each of the detectors 29a to 29n. The amplitude ratio of the detected signal by 31 is calculated. As described above, in this embodiment, sampling is performed at a cycle of 4 msec and 5
Since the average value of the two signals is obtained, the amplitude ratio calculating means 232
Will calculate the amplitude ratio every 20 msec.

Then, the distribution acquisition means 234, every two minutes, the amplitude ratio of each detection signal calculated by the amplitude ratio calculation means 232 within each two-minute period, that is, the detection signal 28as of each band.
The frequency distribution of the amplitude ratio of 28 ns is obtained. That is, the distribution acquisition unit 234 divides the amplitude ratio into a plurality of levels (20 levels in this embodiment) at a predetermined increment (0.05 in this embodiment) for each detection signal 28as to 28ns, and for each level. Calculate the number of occurrences of the amplitude ratio of. Distribution acquisition means 2
FIG. 6 is a graph showing an example of the frequency distribution of the amplitude ratio obtained by 34. The horizontal axis of this graph represents, for example, the amplitude ratio of the detection signal 28as, and the vertical axis represents the number of occurrences (however, it is normalized by the maximum value).

The statistic calculation means 236 detects each detection signal 28as from the frequency distribution obtained by the distribution acquisition means 234.
In this embodiment, the average value and the variance are obtained as numerical values representing the representative value of the amplitude ratio and the degree of dispersion for each 28 ns. Then, the abnormality determination means 23 uses the obtained average value and variance.
8 and outputs signals representing the average value and the variance to a display device to display them. The abnormality determining means 238 determines whether or not there is an abnormality in the machine 10 based on the average value and the variance of the amplitude ratios obtained by the statistic calculating means 236, and a signal indicating the determination result is displayed on the display device 33. Output. Generally, when the machine 10 is operating normally, the spectrum of the detection signal output by the variable amplifier 27 is a wide-band spectrum having no peak at a specific frequency, while the machine 10 becomes abnormal. In this case, the spectrum has a narrow band having a peak at a specific frequency. The abnormality determining means 238 basically determines whether or not the machine 10 is abnormal based on such knowledge.

Specifically, the abnormality determining means 238 calculates the average value of the amplitude ratio for each of the detection signals 28as to 28ns.
It is determined whether or not it is equal to or higher than a preset setting level, and further it is determined whether or not a state in which the average value is equal to or higher than the setting level has continued for a predetermined time or longer. Then, when the state in which the average value is equal to or higher than the set level continues for a predetermined time or longer, the abnormality determining unit 238 determines that the excavator 10 has an abnormality. Further, at this time, the abnormality determining means 238 determines whether the average value of the amplitude ratio exceeds the set level, and further, how long the duration is.
Determine the degree of abnormality.

Here, for example, the frequency band of the abnormal sound caused by the abrasion of the cutter tip is narrow band filter 28.
a, and with respect to the detection signal 28as,
When the average value of the amplitude ratio continues to be equal to or higher than the set level for a predetermined time or longer, the abnormality determining means 238 determines that the cutter tip of the cutter head 12 is worn.

The abnormality determining means 238 also detects each detection signal 2
The variance of the amplitude ratio of each detection signal 28as to 28ns calculated by the statistic calculating unit 236 is calculated every 8as to 28ns.
It is below a preset set level, and it is checked whether or not the state continues for a predetermined time or longer. Detection signal 28as-
When at least one of 28 ns satisfies such a condition, it means that the detection signal output from the variable amplifier 27 includes an abnormal waveform in which the amplitude does not change much and the cycle does not change much. Therefore, the abnormality determination means 23
8 determines that the excavator 10 is abnormal. Then, the abnormality determining means 238 outputs a signal indicating the determination result based on the average value and the variance of such amplitude ratios to the display device 33, and displays the type and degree of abnormality of the excavator 10.

As described above, in the excavator diagnosis apparatus of this embodiment, the sound and vibration generated by the operation of the excavator 10 are quantitatively analyzed by using a statistical method to determine whether the excavator is abnormal. Whether or not and what kind of abnormality is occurring,
Further, it is possible to accurately diagnose the degree of abnormality. Therefore, for example, when it is measured that the rotating torque of the cutter head has exceeded the set value, the cause may be the wear of the cutter tip or the entry of dirt into the bearing of the cutter head drive shaft. Or
Alternatively, it is possible to easily and accurately diagnose whether the cutter head is excavating the rock formation.

Further, what is the average value or the variance of the above-mentioned amplitude ratio of the detection signal, and what are these values?
It is also possible to judge how much the wear of the cutter tip is progressing and to diagnose the life of the cutter tip by observing how it changes with the progress of excavation.

In this embodiment, each detection signal 28as
Although the statistic calculating unit 236 calculates the average value and the variance as the representative value and the dispersion degree of the amplitude ratio for .about.28 ns, the maximum value, the minimum value, the median value, the mode value, and the like are also representative values other than these. As the scatter degree, the statistical deviation calculating unit 236 calculates the standard deviation, the average deviation, the slope of the amplitude ratio distribution curve (for example, the slope of the straight line A in FIG. 8), and the abnormality determining unit 238 uses them. Excavator 1
The abnormality of 0 may be determined.

Further, it is possible not only to make a judgment using only one of the representative value and the degree of dispersion, but also to make a more accurate abnormality diagnosis by using both of them. Further, in the present embodiment, the distribution acquisition unit 234 obtains the frequency distribution every two minutes, but this is only an example, and this time may be set appropriately as needed, and it is set to two minutes. However, the time may be set to, for example, 1 minute, 5 minutes, 10 minutes, or seconds.

[0032]

As described above, in the excavator diagnostic apparatus according to the present invention, first, the sound wave sensor detects a sound or vibration generated during the operation of the excavator, and the amplifier determines the output signal of the sound wave sensor. Amplify to the level. Then, the plurality of narrow band filters extract signals within narrow bands having different center frequencies from the output signal of the amplifier, respectively, while the wide band filter within the predetermined band including abnormal sound or abnormal vibration from the output signal of the amplifier. The signal of is extracted. The amplitude ratio calculating means obtains the amplitudes of the output signals of the narrow band filter and the wide band filter for each predetermined time, and calculates the amplitude ratio of each output signal of the narrow band filter to the output signal of the wide band filter. The distribution acquisition means obtains a frequency distribution within a fixed period of the amplitude ratio of each output signal of the narrow band filter calculated by the amplitude ratio calculation means, and the statistic calculation means calculates the frequency distribution calculated by the distribution acquisition means. Find the numerical value that represents the characteristics of.
Then, the abnormality determining means determines whether or not an abnormality has occurred in the excavator based on the numerical value representing the characteristic of the frequency distribution obtained by the statistic calculating means. Therefore, in the excavator diagnostic apparatus according to the present invention, the sound and vibration generated by the operation of the excavator are quantitatively analyzed using a statistical method, and whether or not an abnormality has occurred in the excavator, and how It is possible to accurately diagnose whether any abnormalities have occurred and to what extent.

Further, based on the quantitative analysis result by the statistical method, that is, by the numerical value representing the characteristic of the frequency distribution, and how the above numerical value changes with the progress of excavation by the excavator. By looking at it, it is possible to judge how much the wear of the cutter tip has progressed and diagnose the life of the cutter tip.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of an excavator diagnostic device according to the present invention.

2 is a schematic configuration diagram showing an earth pressure type shield machine equipped with the diagnostic device of FIG. 1. FIG.

FIG. 3 is a detailed configuration diagram showing the shield machine in FIG. 2 in detail.

FIG. 4 is a graph showing frequency characteristics of a narrow band filter constituting the excavator diagnostic device of FIG. 1.

5 is a graph showing frequency characteristics of a narrow band filter that constitutes the excavator diagnostic device of FIG. 1. FIG.

FIG. 6 is a graph showing frequency characteristics of a wide band filter included in the excavator diagnostic device of FIG. 1.

FIG. 7 is a waveform diagram showing a detection result of a signal that has passed through a wide band filter which constitutes the diagnostic device for the excavator of FIG. 1.

FIG. 8 is a graph showing a frequency distribution of amplitude ratios obtained by a distribution acquisition means that constitutes the excavator diagnostic device of FIG. 1.

[Explanation of symbols]

 10 shield machine 11 shield frame 12 cutter head 12a cutter drive shaft 13 partition wall 14 cutter chamber 15 screw conveyor 16 segment 17 bearing 18 hydraulic motor 19 ventilation device 20 management room 22 computer 23 excavator diagnostic device 23a diagnostic device body 23b signal processing Part 23c Analysis diagnosis part 24 Sound wave sensor 26 Preamplifier 27 Variable amplifier 28a-28n Narrow band filter 29a-29n, 31 Detector 30 Wide band filter 32 AGC circuit 33 Display device 232 Amplitude ratio calculation means 234 Distribution acquisition means 236 Statistic amount calculation Means 238 Abnormality judging means

Claims (7)

[Claims] 1. A sound wave sensor for detecting sound or vibration generated during operation of an excavator, an amplifier for amplifying an output signal of the sound wave sensor to a predetermined level, and a center frequency different from the output signal of the amplifier. A plurality of narrow band filters for respectively extracting signals in a plurality of narrow bands; a wide band filter for extracting a signal in a predetermined band containing abnormal sound or abnormal vibration from the output signal of the amplifier; Amplitude ratio calculating means for calculating the amplitude ratio of the output signals of the bandpass filter and the wideband filter, and the amplitude ratio of each output signal of the narrowband filter to the output signal of the wideband filter, and each output signal of the narrowband filter And a distribution acquisition unit that obtains a frequency distribution of the amplitude ratio within a certain period, and a characteristic of the frequency distribution that is obtained by the distribution acquisition unit. A statistical amount calculating means for obtaining a numerical value, based on the numerical value representing the characteristic of the frequency distribution obtained by the statistical amount calculating means, an abnormality determining means for determining whether or not an abnormality has occurred in the machine, An excavator diagnostic device characterized by being provided with. 2. The numerical value representing the characteristic of the frequency distribution includes, as a representative value of the amplitude ratio, an average value of the amplitude ratio,
An excavator diagnostic device including at least one of a maximum value, a minimum value, a median value, and a mode value. 3. The numerical value representing the characteristic of the frequency distribution has at least one of a variance of the amplitude ratio, a standard deviation, an average deviation, and a slope of a curve representing the frequency distribution, as a dispersion degree of the amplitude ratio. Excavator diagnostic device including one. 4. The excavator diagnosis apparatus according to claim 2, wherein the abnormality determining means determines that an abnormality has occurred in the excavator when the representative value satisfies a predetermined condition. 5. The excavator diagnosis apparatus according to claim 3, wherein the abnormality determining means determines that an abnormality has occurred in the excavator when the dispersion degree satisfies a predetermined condition. 6. The excavator diagnosing device according to claim 1, further comprising display means for displaying a determination result by said abnormality determining means. 7. The excavator diagnostic device according to claim 1, wherein the sound wave sensor is provided in a cutter chamber partition wall of the excavator.