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JP2006254376

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DESCRIPTION JP2006254376
PROBLEM TO BE SOLVED: To provide a sound collecting device capable of selectively
incorporating the frequency in correspondence with a plurality of places such as an engine and
improving the diagnostic accuracy. A sound collecting unit (11) having a cone-shaped wall
surface and a parabolic wall formed by expanding the front side thereof and resonance sound of
a predetermined frequency are extracted from the sound collected by the sound collecting unit
(11) The sound collector 10 is configured to include the resonance cylindrical portion 12 having
a predetermined cylindrical length and the acoustic sensor 13 connected to the cylindrical
proximal end of the resonance cylindrical portion 12. An acoustic analysis system that analyzes
an acoustic signal from the sound collection device 10 to detect an abnormal sound, comprising:
a filter circuit that switches the acoustic signal to a high band or a low band and performs filter
processing; and the acoustic signal subjected to the filter processing And a data processing unit
46 for analyzing. [Selected figure] Figure 1
Sound collector and acoustic analysis system using the same
[0001]
The present invention relates to a sound collecting device for collecting operation sound
generated from a power device such as an engine, and an acoustic analysis system for analyzing
the sound signal using this sound collecting device and diagnosing the operating condition of the
device. .
[0002]
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1
Conventionally, when detecting an abnormality such as an engine of a car, the operation sound is
detected using a sound collector having an acoustic sensor such as a microphone, and then noise
is removed by a filter or the like to obtain necessary sound. I try to take out the signal.
For example, sound from the engine is detected by a microphone, unnecessary bands of the
electric signal output from the microphone are cut off by a filter, and the output signal of the
filter is processed by a signal processing device. The processed electrical signal is compared with
the normal electrical signal measured in advance to diagnose the presence or absence of
abnormality. For example, when checking a problem in the engine bearing portion, a component
of a band including the natural frequency of the bearing in the acoustic signal is an object of
diagnosis. For example, the following techniques are known in relation to such a sound collection
device.
[0003]
In Patent Document 1, a sound reflection inner wall having a paraboloid shape is formed having
a focal point at a predetermined focal distance from the apex of one end and an opening at the
other end facing the apex, and the apex and the opening A sound collection device that separates
the collected sound from ambient noise and performs high SN ratio sound collection so that the
distance between the two and the focal length has a value 10 or more times the focal length Is
disclosed. In Patent Document 2, a cone-shaped inner wall having an opening and having a
smaller cross-sectional area toward the inner side is formed, and a sound sensor for receiving
sound incident from the opening is provided in the vicinity of the apex of the cone. It is disclosed
that the sound radiated is separated from ambient noise and collected. JP-A-7-231495 JP-A-8172692
[0004]
However, in the sound collecting apparatus of the prior art, the acoustic sensor such as a
microphone does not have a function to selectively and directly introduce the sound of a specific
frequency from the sound source, and the diagnostic accuracy depends on the filtering of the
sound signal. Therefore, in the case of a specific sound source such as an engine, there is a
problem that the detection sensitivity of sound of a specific frequency is lowered, or the device
system is complicated to lack economy and maintainability.
[0005]
In the sound collectors described in Patent Document 1 and Patent Document 2, the geometric
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2
configuration of the paraboloid shape of the rotation and the inner wall of the sound reflection
formed in a conical shape is constant, so that the sound acquired by the acoustic sensor is There
is a problem that the sensitivity of the specific frequency can not be adjusted, and the detection
accuracy can not be improved.
[0006]
The present invention has been made to solve the above-described conventional problems, and it
is possible to selectively introduce the frequency corresponding to a plurality of places such as
an engine, and a sound collecting device capable of enhancing the diagnostic accuracy. Intended
to be provided.
Another object of the present invention is to provide an acoustic analysis system using a sound
collection device which can increase the diagnostic efficiency by feedback processing of an
acoustic signal acquired by an acoustic sensor and is excellent in economy and maintainability.
Do.
[0007]
The sound collecting device according to claim 1 of the present invention made to solve the
above-mentioned conventional problems has a sound collecting portion which is formed to have
a cone-shaped wall surface or a parabolic wall surface by expanding the front side thereof and
Providing a resonance cylindrical portion having a predetermined cylindrical length for
extracting resonance sound of a predetermined frequency from the sound collected by the sound
collection unit; and an acoustic sensor connected to a cylindrical proximal end of the resonance
cylindrical portion. It is characterized by
[0008]
According to a second aspect of the present invention, in the first aspect, the resonance
cylindrical portion is provided with a resonance frequency setting unit for setting a resonance
frequency of sound acquired by expanding and contracting the cylinder length. It has a feature.
[0009]
An acoustic analysis system according to claim 3 of the present invention is an acoustic analysis
system that analyzes an acoustic signal from a sound collection device to detect an abnormal
sound, and switches the acoustic signal to a high band or a low band to filter A filter circuit for
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processing and a data processing unit for analyzing the filtered acoustic signal are provided.
[0010]
In the sound system according to the present invention, in claim 3, the appropriate resonance
frequency is set based on the data of the sound signal input to the data processing unit, and the
resonance frequency setting unit of the sound collection device is operated. The present
invention is characterized in that the cylinder length of the part is adjusted to the appropriate
resonance frequency.
[0011]
According to the sound collection device of the present invention, since the resonance sound is
taken into the acoustic sensor via the resonance cylindrical portion that extracts the resonance
sound of the predetermined frequency from the sound, the sound of the specific frequency
generated from the fault location such as the engine Can be selectively incorporated, and
detection sensitivity and diagnostic accuracy to abnormal sound can be enhanced.
In addition, the resonance cylindrical portion may be provided with a resonance frequency
setting unit for setting the resonance frequency of the acquired sound, and the detection
sensitivity and the like for identifying a plurality of abnormality occurrence points can be further
enhanced.
[0012]
Further, according to the acoustic analysis system of the present invention, the acoustic signal
acquired from the sound collection device is switched to the high band or the low band, the filter
processing is performed, and the acoustic signal is analyzed, thereby performing data processing
with excellent reliability. be able to.
Furthermore, since the appropriate resonance frequency can be set based on the data of the
input acoustic signal to adjust the cylinder length of the resonance cylindrical portion to the
appropriate resonance frequency, the feedback processing of the acoustic signal acquired by the
acoustic sensor It is possible to provide an acoustic analysis system excellent in diagnostic
accuracy.
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[0013]
Embodiment 1 FIG. 1 (a) is a front cross-sectional view of a sound collector of Embodiment 1, and
FIG. 1 (b) is a side view thereof.
In FIG. 1, 10 is a sound collecting device of the first embodiment, 11 is a sound collecting portion
formed with a cone-shaped wall made of a wood material or a synthetic resin material, and 12 is
connected to the base end of the sound collecting portion 11 An inner diameter D for extracting
resonance sound of a predetermined frequency from the collected sound, a resonance cylindrical
portion of a cylindrical length L, 13 is an acoustic sensor such as a microphone or a piezoelectric
element connected to the cylindrical base end of the resonance cylindrical portion 12 It is.
[0014]
As illustrated, the sound collecting unit 11 is formed in a truncated cone shape whose cross
section is a short side D, a long side E, and a height H, and the opened short side matches the
inner diameter D of the resonance cylindrical portion 12 It is supposed to be connected.
The sound collecting unit 11 is formed in a megaphone shape by a synthetic resin material such
as polyethylene or polystyrene, or a light metal material such as an aluminum alloy, and the
thickness, the material, and the like can be set to maintain predetermined acoustic
characteristics.
[0015]
The resonance cylindrical portion 12 is a member disposed integrally with the rear end of the
sound collecting portion 11 or separately so as to be detachable from the sound collecting
portion 11.
The cylindrical length L and the cylindrical inner diameter D of the resonance cylindrical portion
12 are respectively set to appropriate values corresponding to the resonance frequency of a
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specific sound source such as an engine. In addition, the material property, thickness, and the
like of the resonance cylindrical portion 12 are applied based on acoustic experiments and the
like. Sound of resonance can be efficiently extracted by the length of the cylinder of the
resonance cylindrical portion 12.
[0016]
That is, since the bottom of the cylindrical portion of the resonance cylindrical portion 12 is a
fixed end, a standing wave whose pressure value is always maximum can be collected. The
resonance can be a standing wave where the amplitude of the bottom displacement is minimal
when one of the ends of the cylinder (bottom) is closed. The pressure fluctuation is maximized at
a position where the positional fluctuation amplitude is minimum, and by placing the sensor
element on the bottom of the cylinder, the maximum pressure fluctuation can be applied to the
sensor element. As described above, by using the closed portion as the sensor surface and
detecting the pressure wave, the most efficient sound collection becomes possible. In addition,
when the resonance by a cylindrical part is equal to a quarter wavelength of a certain frequency
normally, a standing wave of that frequency appears, and when observed from the outside, this
can be regarded as a resonance.
[0017]
The tip end of the cylinder has an open structure, that is, a so-called free end structure. In order
to maximally emit sound due to resonance from this free end, it is necessary to have a standing
wave with the maximum amplitude at the free end. Therefore, the standing wave with the
maximum amplitude at the entrance of the cylinder and the minimum amplitude at the fixed end
of the cylinder bottom is a quarter of the wavelength. The sound wave is a compressional wave of
air, and if it penetrates inside the cylinder, reflection occurs on the side surface etc. Therefore, if
the diameter of the cylinder is half the wavelength of the resonance frequency, a standing wave
is generated in the cylinder diameter direction Not desirable.
[0018]
The inner diameter D of the resonance cylindrical portion 12 is preferably in the range of 6 mm
or more and less than 10 mm. This makes selection easier because there are few types of
resonance frequencies when the cylinder length is set. The rear end of the sound collecting
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portion 11 and the resonance cylindrical portion 12 have no break or step in the connecting
portion, so a part of the cone-shaped sound collecting portion 11 near the connecting portion
also becomes a part of the cylinder An effect can be produced such that the length of the cylinder
is artificially increased.
[0019]
The acoustic sensor 13 is a circular sensor element whose acoustic detection end receives the
sound pressure from the resonance cylindrical portion 12 has a diameter D. As this sensor, other
than a general condenser microphone, an electret microphone, a sensor using a piezoelectric
element, or the like can be applied. In the electret microphone, a thin film of an electret element
having a metal coating and a metal plate are disposed in parallel, and the thin film vibrates due to
sound pressure so that current flows between the metal coating and the metal plate. . The
electret element is a material such as polymer or ceramic that has the property that the charge
remains even after the external electric field disappears, and the sensor using the piezoelectric
element uses the electromotive force when the crystal generates strain due to the sound pressure
It is a thing.
[0020]
As described above, since the sound collecting apparatus 10 according to the first embodiment
includes the resonance cylindrical portion 12 having a predetermined cylindrical length L for
extracting resonance sound of a predetermined frequency from the sound, the failure location of
the engine or the like It is possible to selectively take in the sound of a specific frequency
generated from the above, and to improve the detection sensitivity and the diagnostic accuracy to
the abnormal sound.
[0021]
Second Embodiment FIG. 2 (a) is a front cross-sectional view of a sound collection device
according to a second embodiment, and FIG. 2 (b) is a side cross-sectional view and an exploded
description of a resonance frequency setting unit of the same sound collection device. FIG.
In FIG. 2, 20 is a sound collecting apparatus according to the second embodiment, 21 is a sound
collecting unit for taking in sound from an object to be measured such as an engine through a
cone-shaped or parabolic wall, and 22 is a sound collecting unit. A resonance cylindrical portion
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connected to the base end of the portion 21 and provided with an outer cylinder 22b that slides
on the inner cylinder 22a and the inner cylinder 22a; 23 is an acoustic sensor connected to the
cylindrical base end of the resonance cylinder 22; Is a resonance frequency setting unit for
setting the cylindrical length L of the resonance cylindrical portion 22 to a predetermined value.
As the sound collecting unit 20 and the acoustic sensor 23, those having the same material and
configuration as those of the first embodiment can be applied. The sound collecting unit 21 may
be omitted as necessary to directly connect the opening end of the resonance cylindrical portion
22 to the object to be measured, and this may be applied as a sound collecting device. As shown
in FIG. 2 (b), the resonance frequency setting unit 24 is provided with a guide pin 24a protruding
from the inner cylinder 22a, and a guide that is provided on the outer cylinder 22b so as to be
curved in an arc and the guide pin 24a is fitted. And a groove 24b. As a result, by gripping and
rotating the outer cylinder 22b of the resonance cylindrical portion 22, the guide pin 24a of the
inner cylinder 22a restricted by the locking member (not shown) is moved in the guide groove
24b of the outer cylinder 22b. Thus, the cylinder length L of the resonance cylindrical portion 22
is set to a predetermined value, so that the sound having the resonance frequency is efficiently
acquired. As a drive mechanism of the resonance frequency setting unit, a servomotor or cylinder
mechanism for relatively slidingly expanding and retracting a double cylinder consisting of a
cylinder and an outer cylinder is provided, and this is automatically or manually operated via a
control device such as a microcomputer. It can also be controlled by
[0022]
As described above, the sound collecting apparatus 20 according to the second embodiment is
configured to include the resonance frequency setting unit 24. Therefore, in addition to the
effects of the first embodiment, the sound collecting apparatus 20 is acquired by the resonance
cylindrical portion 22. The resonant frequency of sound can be set appropriately. As a result, it is
possible to specify with high accuracy the abnormal sound generated from a plurality of
locations such as an engine and the operation state thereof. Furthermore, in cooperation with the
data processing device connected to the sound collection device 20, based on the analysis result
of the acoustic signal obtained by the sound collection device 20, the cylindrical length L of the
resonance cylindrical portion 22 is set to the resonance frequency It is also possible to perform
feedback processing to an appropriate value using the unit 24 and perform optimization
processing so as to efficiently acquire a resonance acoustic component.
[0023]
Third Embodiment FIG. 3 (a) is a front cross-sectional view of a sound collector of a third
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embodiment, and FIG. 3 (b) is a left side view of the sound collector. In FIG. 3, reference numeral
30 denotes a sound collecting apparatus according to the third embodiment, 31 denotes a sound
collecting unit having a parabolic wall for taking in sound from the object to be measured, and
32 denotes an open front of the sound collecting unit 31. A resonance cylindrical portion
attached at the center of the portion via the support member 34 in the opposite direction to the
object to be measured, and 33 is an acoustic sensor connected to the cylindrical proximal end of
the resonance cylindrical portion 32. The resonance cylindrical portion 32 is disposed such that
the opening is in the opposite direction to that of the first and second embodiments, and the
opening is at the focal position of the parabolic wall surface. In addition, the thing of the raw
material and the structure similar to the said Embodiment 1 is applied to the sound collection
part 30 and the acoustic sensor 33. FIG. The resonance cylindrical portion 32 is provided with a
slide mechanism whose cylinder length can be extended and contracted by a servomotor (not
shown) which is a resonance frequency setting portion, and it is also possible to set it to a
prescribed cylinder length. .
[0024]
As described above, since the sound collecting apparatus 30 of the third embodiment has the
resonance cylindrical part 32 opened in the opposite direction at the focal position of the
parabolic wall to be the sound collecting part 31, the parabolic wall is formed. By combining the
sound collection efficiency possessed by the above and the frequency selectivity of the resonance
cylindrical portion 32, it is possible to acquire highly reliable acoustic data while being excellent
in directivity with respect to the object to be measured.
[0025]
Fourth Embodiment FIG. 4 is a block diagram of an acoustic analysis system using a sound
collection apparatus according to a fourth embodiment.
In FIG. 4, 40 is an acoustic analysis system according to the fourth embodiment, 41 is an
amplifier for amplifying an analog acoustic signal obtained from the sound collector 10
according to the first embodiment, and 42 is a high wavelength band filter side of the acoustic
signal. Alternatively, a switching circuit for switching to the low wavelength band filter side, a
high wavelength band filter circuit (cutoff frequency variable high pass filter) 43 for extracting
high wavelength components from the input acoustic signal, and 44 for extracting low
wavelength components A low wavelength filter circuit (cutoff frequency variable high pass
filter) 45 is a switching circuit for dividing an input signal in time and outputting a value
obtained by subtracting the value of time (t-1) from time t as a signal of time t A differential
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circuit 46 is a data processing unit comprising a microcomputer etc. 47 is a liquid crystal panel
or LED for displaying data analysis results etc. Display unit of, 49 is a battery for supplying a
predetermined power to the analog circuit power supply 49a and the microcomputer power
supply 49b.
[0026]
The acoustic analysis system 40 switches the acoustic signal acquired via the resonance
cylindrical portion 11 of the sound collection device 10 to a high band or a low band, and
performs filter processing by the high wavelength band filter circuit 43 or the low wavelength
band filter circuit 44 Since the acoustic signal is analyzed by the data processing unit 46, data
processing with excellent reliability and efficiency can be performed.
[0027]
Table 1 shows, for example, the resonance formula (L = (2 (n-1) +1) × kV / 4f, where f:
resonance frequency, L: cylinder length, V: speed of sound in air, n: resonance wave By
comparison data of the cylinder length L of the resonance cylindrical part obtained by applying a
multiple of the wavelength (the order of the resonance wave, k: unit conversion factor) etc. when
the is obtained, and the corresponding resonance frequency f FIG. 5 shows a cylinder of a
resonance cylindrical portion obtained by extracting data in the case where the cylinder inner
diameter D is D = 8 mm and the order n of the resonance wave is 1, 2, 3, 4 from the data of Table
1 It is a graph which shows the relationship between length L and resonance frequency f.
[0028]
As shown in FIG. 5, in the case where the cylindrical inner diameter D of the resonance
cylindrical portion 11 is 8 mm, for example, a first resonance wave, a second resonance wave, a
third resonance wave and a fourth resonance wave corresponding to the frequency f = 20 KHz. It
can be seen that the cylinder lengths L (sensor positions), which are respectively, are
approximately 2 mm, approximately 11 mm, approximately 19 mm, and approximately 30 mm.
Conversely, when the cylindrical length L of the resonance cylindrical portion 11 is fixed to L = 4
mm, the resonance frequency f changes so as to become maximum values at about 20 KHz and
40 KHz, for example.
Therefore, the cylinder length L is set to an appropriate value such that a resonance phenomenon
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can be obtained for each application condition, and the sound from the sound collection unit 11
is acquired via the resonance cylindrical unit 12 and data processing is performed Thus, it can be
understood that it is possible to efficiently extract the component of the specific frequency from
the acoustic signal and to improve the analysis accuracy and the diagnosis accuracy of the failure
location and the like.
[0029]
Thus, the acoustic analysis system 40 according to the fourth embodiment switches the acoustic
signal acquired through the resonance cylindrical portion 12 of the sound collection device 10 to
the high band or the low band, and performs filter processing to analyze this acoustic signal.
Data processing with excellent reliability can be performed, and a large number of such data is
stored in a database, and the position of abnormal sound generated in an engine or the like is
accurately compared with the acquired data of acoustic signals. It is possible to identify and to
judge the quality of the operation status.
[0030]
Fifth Embodiment FIG. 6 is a block diagram of an acoustic analysis system using a sound
collection device according to a fifth embodiment.
As shown in FIG. 6, in the acoustic analysis system of the fifth embodiment, the analog acoustic
signal acquired from the sound collection device 20 of the second embodiment is amplified by
the amplifier 41, and the high wavelength band filter circuit 43 or the low wavelength band filter
After filtering by the circuit 44, analysis processing of the data taken in by the data processing
unit 46 is performed through the switching differentiation circuit 45, and feedback processing of
resetting the cylinder length L is performed based on the analysis result. That is, the cylindrical
length L of the resonance cylindrical portion 22 is set to an appropriate value by controlling it
using the resonance frequency setting unit 24 provided with a servomotor or the like. The
acoustic analysis system 50 of the fifth embodiment sets the appropriate resonance frequency
based on the data of the acoustic signal input via the sound collection device 20, and adjusts the
cylinder length L of the resonance cylindrical portion 22 to the appropriate resonance frequency.
Feedback processing is performed. Thus, data analysis processing can be performed based on the
data of the reconstructed acoustic signal, and the analysis result can be displayed on the display
unit 47, thereby enhancing the reliability and stability of the acoustic signal acquired by the
acoustic sensor, When diagnosing the operation state of power plants, such as an engine, the
acoustic analysis system excellent in the diagnostic accuracy can be provided.
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[0031]
As mentioned above, although the sound collection apparatus which concerns on this
Embodiment, and the acoustic analysis system using the same were demonstrated, this invention
is not limited to the thing of these Embodiment. That is, the present invention is characterized in
that the specific frequency component is effectively extracted from the sound acquired from the
sound collecting unit by utilizing the resonance phenomenon in the resonance cylindrical
portion, and the concept corresponding to this is provided. Those are the scope of application of
the present invention. For example, in the present embodiment, the engine has been described as
an example of the object to be measured, but it can also be used to determine the operating state
of a power plant or the like in a production facility.
[0032]
(A) It is front sectional drawing of the sound collector of Embodiment 1. FIG. (B) It is a side view.
(A) It is front sectional drawing of the sound collector of Embodiment 2. FIG. (B) It is side surface
sectional drawing and decomposition ¦ disassembly explanatory drawing in a resonance
frequency setting part. (A) Front sectional drawing of the sound collector of Embodiment 3. FIG.
(B) It is a side view of the sound collecting device. FIG. 14 is a configuration diagram of an
acoustic analysis system using the sound collection device of a fourth embodiment. It is a graph
which shows the relationship between the cylinder length L of a resonance cylindrical part, and
the resonance frequency f. FIG. 18 is a configuration diagram of an acoustic analysis system
using the sound collection device of a fifth embodiment.
Explanation of sign
[0033]
10 Sound Collection Device of First Embodiment 11 Sound Collection Unit 12 Resonance
Cylindrical Part 13 Acoustic Sensor 20 Sound Collection Device of Second Embodiment 21 Sound
Collection Unit 22 Resonance Cylindrical Part 22a Inner Cylinder 22a Outer Cylinder 23 Acoustic
Sensor 24 Resonance Frequency Setting Section 24a Guide pin 24b Guide groove 30 Sound
collecting device 31 of the third embodiment 31 sound collecting unit 32 resonance cylindrical
portion 33 acoustic sensor 34 support member 40 acoustic analysis system of the fourth
embodiment 41 amplifier 42 switching circuit 43 high wavelength band filter circuit (Cut off
frequency variable high pass filter) 44 Low wavelength band filter circuit (cut off frequency
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variable high pass filter) 45 Switching differentiation circuit 46 Data processing unit 47 Display
unit 49 dry cell 49 a Analog circuit power supply 49 b Microcomputer power supply 50 Acoustic
analysis system of the fifth embodiment
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