JP2007101182A - Ultrasound velocity measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasound velocity measuring instrument for efficiently measuring the sound velocity of ultrasonic wave propagating through a certain kind of material, such as a sound absorption material placed in two kinds of different gases. <P>SOLUTION: This ultrasound velocity measuring instrument is equipped with a container, alternately filled with the prescribed two kinds of different gases, a material put-in/put-out means for causing the the kind of material placed in the container to be put into or out with respect to a prescribed measurement position, an ultrasonic transmission/reception means placed in the container and having an ultrasonic transmission sensor and an ultrasonic reception sensor, disposed at the prescribed measurement position interposed therebetween, and an ultrasonic wave velocity calculation means for severally calculating the velocity of the ultrasonic passing through the kind of material in the two kinds of different gas atmospheres, based on data obtained by the transmission/reception means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ultrasonic sound velocity measuring device, for example, efficiently measuring the sound velocity of an ultrasonic wave passing through a certain material such as a sound absorbing material, and thereby, the physical properties of a certain material such as a sound absorbing material. It relates to what was devised so that it can be analyzed.

For example, it is known that the sound absorption coefficient of a porous sound absorbing material has a great relationship with “flow resistance”. The measurement method of the “flow resistance” is defined in the ISO 9053 standard. Further, there are “Tortuality” and “Characteristic Length” as physical property values that have a deep causal relationship with the “flow resistance”. That is, in order to elucidate “flow resistance” in detail, information on physical property values such as “Tortuality” and “Characteristic Length” is required.
The “Characteristic Length” includes two types of “Viscous Characteristic Length” and “Thermal Characteristic Length”.

  Further, it is known that the physical property values such as “Tortuality” and “Characteristic Length” can be obtained by measuring the velocity of ultrasonic waves propagating in a sound absorbing material installed in two different kinds of gases.

  The conventional configuration has the following problems. As described above, it is known that physical properties such as “Tortuosity” and “Characteristic Length” can be obtained by measuring the velocity of ultrasonic waves propagating in a sound absorbing material installed in two different types of gases. However, there was no effective device for measuring the speed of ultrasonic waves propagating through the sound-absorbing material installed in two different gases.

  Although not directly related to the present application, there are, for example, Patent Document 1 and Patent Document 2 as prior art.

Japanese Patent Laid-Open No. 7-147441 JP 2003-240636 A

  The present invention has been made based on such points, and the object is to efficiently measure the speed of ultrasonic waves propagating in a certain kind of material such as a sound absorbing material installed in two different kinds of gases. It is an object of the present invention to provide an ultrasonic sound velocity measuring apparatus capable of doing so.

In order to achieve the above object, an ultrasonic sound velocity measuring apparatus according to claim 1 of the present invention provides a predetermined measurement of a container in which two different kinds of gases are alternately filled and a certain kind of material installed in the container. A material intruding means for intruding with respect to a position, an ultrasonic transmitting / receiving means installed in the container, and an ultrasonic transmission sensor and an ultrasonic receiving sensor arranged with the predetermined measurement position interposed therebetween, and the ultrasonic transmission / reception Ultrasonic velocity calculation means for calculating the velocity of ultrasonic waves that pass through the certain kind of material in the two different types of gas atmospheres based on the data obtained by the means, respectively, It is.
The ultrasonic sound velocity measuring device according to claim 2 is the ultrasonic sound velocity measuring device according to claim 1, wherein the two different kinds of gases are air, acoustic impedance is larger than air, and kinematic viscosity is higher. It is characterized by being a gas that is not more than 1.5 times air.
An ultrasonic sound velocity measuring device according to claim 3 is the ultrasonic sound velocity measuring device according to claim 2, wherein the gas having an acoustic impedance larger than air and having a kinematic viscosity 1.5 times or less that of air is argon. It is gas (Ar), oxygen gas (O ₂ ), or carbon dioxide gas (CO ₂ ).
According to a fourth aspect of the present invention, there is provided the ultrasonic sound velocity measuring device according to the first aspect, further comprising a gas supply / exhaust means for supplying / exhausting the two different kinds of gases. It is a feature.
The ultrasonic sound velocity measuring device according to claim 5 is the ultrasonic sound velocity measuring device according to claim 4, wherein the gas supply / exhaust means supplies the two different kinds of gases into the container. Means and gas exhaust means for exhausting the two different kinds of gases from the inside of the container.
An ultrasonic sonic velocity measuring device according to claim 6 is the ultrasonic sonic velocity measuring device according to claim 1, wherein the predetermined two kinds of different gases are alternately filled in a container, and the above-mentioned certain kinds of gases are filled in each atmosphere. The material is infested at a predetermined measurement position, data is obtained with and without a certain type of material, and the ultrasonic velocity is calculated based on the data with and without a certain type of material in each atmosphere. The ultrasonic velocity is calculated by the calculating means.
An ultrasonic sound velocity measuring device according to claim 7 is the ultrasonic sound velocity measuring device according to claim 1, wherein the certain material is a sound absorbing material.

As described above, according to the ultrasonic sound velocity measuring apparatus according to the present invention, a container in which two different kinds of different gases are alternately filled and a certain material installed in the container with respect to a predetermined measurement position. It is obtained by means of a material intruding means for intruding, an ultrasonic transmission / reception means in which an ultrasonic transmission sensor and an ultrasonic reception sensor are arranged in the container and sandwiching the predetermined measurement position, and the ultrasonic transmission / reception means. The ultrasonic velocity calculating means for calculating the velocity of the ultrasonic wave passing through the certain kind of material in the two different types of gas atmospheres based on the different data. It is possible to easily measure the speed of sound of a desired ultrasonic wave in two kinds of gas atmospheres, thereby easily and accurately analyzing the physical properties of certain materials. It became a jar.
In addition, if the two different gases described above are air and a gas whose acoustic impedance is greater than that of air and whose kinematic viscosity is 1.5 times that of air or less, the desired measurement is performed with high accuracy. can do.
In addition, a gas having an acoustic impedance greater than that of air and a kinematic viscosity of 1.5 times or less that of air,
When argon gas (Ar), oxygen gas (O ₂ ), or carbon dioxide gas (CO ₂ ) is used, the above-described effect becomes more reliable.
Moreover, when the gas supply / exhaust means for supplying / exhausting the two predetermined different gases is provided, the two different types of gases can be easily replaced.
Further, when a certain kind of material is used as a sound absorbing material, an excellent effect is exhibited in developing a new sound absorbing material.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing an overall configuration of an ultrasonic sound velocity measuring apparatus according to the present embodiment. First, there is a container 1, and two different kinds of gases are alternately filled in the container 1. The container 1 is configured in a hermetically sealed state, and a plurality of legs 2 are provided at the lower end, and the container 1 is installed on the floor 4 via the legs 2.

The container 1 is provided with a configuration for supplying and exhausting the two kinds of gases. In the case of this embodiment, air and argon gas (Ar) are used as the two kinds of gases. These two types of gases will be described in detail later.
First, the bottom plate of the container 1 is provided with an air introduction port 3 for filling the container 1 with the air, and an end plug 8 is detachably attached to the air introduction port 3. Yes.

  An argon gas supply means 5 for supplying the argon gas (Ar) is connected to the container 1 via a tube 7. The tube 7 is connected to the bottom plate of the container 1. An air / argon gas exhaust means 9 for exhausting air or argon gas filled in the container 1 to the outside of the container 1 is connected to the container 1 via a tube 11. The tube 11 is connected to the bottom plate of the container 1.

  When the container 1 is initially filled with air, the end plug 8 attached to the air introduction port 3 is removed. Thereby, air is introduced and filled into the container 1. Next, when the air and the argon gas are exchanged, the air is exhausted through the air / argon gas exhausting means 9 and the argon gas is supplied by the argon gas supplying means 5.

  The container 1 is provided with ultrasonic transmission / reception means 13. First, an ultrasonic oscillator 15 is installed outside the container 1, while an ultrasonic transmission sensor 17 is installed inside the container 1. An ultrasonic reception sensor 19 is installed so as to face the ultrasonic transmission sensor 17. The ultrasonic transmission sensor 17 and the ultrasonic reception sensor 19 are supported by a support member 20. The ultrasonic receiving sensor 19 is connected to a signal analyzer 21 installed outside the container 1. The ultrasonic oscillator 15 and the signal analyzer 21 are connected to the calculation means 23.

  In the container 1, a material intrusion unit 27 for selectively causing the sound absorbing material 25, which is a certain kind of material, to appear and disappear at a predetermined measurement position between the ultrasonic transmission sensor 17 and the ultrasonic reception sensor 19 is installed. Yes. The material intruding means 27 includes a sound absorbing material gripping part 29 for gripping the sound absorbing material 25, a support part 31 configured to support the sound absorbing material gripping part 29 and to be rotatable. The sound absorbing material 29 is caused to appear and disappear at a predetermined measurement position by rotationally driving the support portion 31 by the drive motor 28.

  The sound absorbing material 29 is carried into and out of the container 1. First, the container 1 is formed with an opening 1 a, and the opening 1 a is appropriately opened and closed by the opening / closing lid 6. It is configured. And when carrying in and carrying out the sound absorption material 25 in the container 1, the said opening-and-closing lid body 6 is rotated, for example, and the opening part 1a is open | released. On the other hand, the support part 31 is rotated to position the sound absorbing material gripping part 29 on the opening 1a side. In this state, the sound absorbing material 25 is carried in and out through the opening 1a.

  A pressure gauge 33 is attached to the upper portion of the container 1. Two different kinds of gases are exchanged while monitoring the display of the pressure gauge 33.

Next, two different types of gases will be described in detail.
First, in selecting a gas to be used, an S / N ratio (signal-to-noise ratio) at the time of measurement is taken into consideration. For example, some gases have the property that the acoustic impedance is smaller and the kinematic viscosity is larger than air. For example, helium gas (He) is available. The sound wave propagating through the sound absorbing material 25 installed in the helium gas is strongly attenuated, so that a higher density material or a thicker material ensures a better S / N ratio (signal to noise ratio). Will become difficult. Moreover, it is necessary to process the thinner the thicker the thicker the material. However, it is extremely difficult to thinly process the fiber-based sound absorbing material 25 into a uniform thickness. That is, helium gas is not suitable for this kind of sound velocity measurement.

On the other hand, in the gas, there exists a gas that satisfies the condition that the acoustic impedance is larger and the kinematic viscosity is smaller than that of air. Examples of such gas include argon gas (Ar), oxygen gas (O ₂ ), carbon dioxide gas (CO ₂ ), and the like. If these gases are used, the attenuation is comparable to that of air, and the S / N ratio (signal-to-noise ratio) can be measured as much as that of air. Therefore, in this embodiment, argon gas (Ar) is used. That is, two different types of gas, air and argon gas (Ar), are used.

The argon gas (Ar), oxygen gas (O ₂ ), or carbon dioxide gas (CO ₂ ) satisfies the condition that the acoustic impedance is large and the kinematic viscosity is small compared to air, and the kinematic viscosity is 1 of air. It is less than 5 times.
Specifically, while the kinematic viscosity of air is (1.51 × 10 ⁻⁵ m ² / s), the kinematic viscosity of argon is (1.34 × 10 ⁻⁵ m ² / s), oxygen Has a kinematic viscosity (1.53 × 10 ⁻⁵ m ² / s) and carbon dioxide has a kinematic viscosity (0.8 × 10 ⁻⁵ m ² / s). From the table). Therefore, the dynamic viscosity of any gas is 1.5 times or less of the dynamic viscosity of air.
The kinematic viscosity of the helium is (11.8 × 10 ⁻⁵ m ² / s), which is far from the condition of 1.5 times or less the dynamic viscosity of air.

Incidentally, FIG. 2 is a diagram showing the ultrasonic sound velocity measurement result of the sound absorbing material 25 installed in the air, FIG. 3 is a diagram showing the ultrasonic sound velocity measurement result of the sound absorbing material 25 installed in the argon gas (Ar), FIG. These are figures which show the ultrasonic sound speed measurement result of the sound-absorbing material 25 installed in helium gas (He). 2, 3, 4, the measuring air, argon gas, in an atmosphere of helium gas, density of 41.7kg ^/ m 3, the speed of the ultrasound passing through the sound absorbing material 25 of 73.9kg / ^{m 3} It is shown. The vertical axis is the sound velocity (m / s), and the horizontal axis is the frequency (kHz). As shown in FIGS. 2 and 3, effective data can be obtained in the case of air or argon gas. On the other hand, helium gas has too much noise and cannot be effective data.

The operation will be described based on the above configuration.
First, the velocity of ultrasonic waves propagating through the sound-absorbing material 25 that is filled in the container 1 and installed in the air is measured. At this time, first, the sound absorbing material 25 is set at a predetermined measurement position between the ultrasonic transmission sensor 17 and the ultrasonic reception sensor 19 by the material projecting and retracting means 27. In this state, a signal is sent from the ultrasonic oscillator 15 to the ultrasonic transmission sensor 17. Then, the signal from the ultrasonic reception sensor 17 is analyzed by the signal analyzer 21.
Next, the sound absorbing material 25 is retracted from a predetermined measurement position between the ultrasonic transmission sensor 17 and the ultrasonic reception sensor 19 by the material projecting / removing means 27. In this state, a signal is sent from the ultrasonic oscillator 15 to the ultrasonic transmission sensor 17. Then, the signal from the ultrasonic reception sensor 17 is analyzed by the signal analyzer 21.
That is, data is acquired in two cases, the case where the sound absorbing material 25 is present and the case where the sound absorbing material 25 is absent.

Next, the same measurement is performed by replacing the gas in the container 1 from air to argon gas (Ar). That is, the air in the container 1 is discharged by the air / argon gas exhaust means 9. At that time, the pressure gauge 33 is used for confirmation. Next, argon gas is filled into the container 1 by the argon gas supply means 5. This is also confirmed by the pressure gauge 33.

Next, the same measurement as in the case of air is performed. First, the sound absorbing material 25 is set at a predetermined measurement position between the ultrasonic transmission sensor 17 and the ultrasonic reception sensor 19 by the material projecting / removing means 27. In this state, a signal is sent from the ultrasonic oscillator 15 to the ultrasonic transmission sensor 17. Then, the signal from the ultrasonic reception sensor 17 is analyzed by the signal analyzer 21.
Next, the sound absorbing material 25 is retracted from a predetermined measurement position between the ultrasonic transmission sensor 17 and the ultrasonic reception sensor 19 by the material projecting and retracting means 27. In this state, a signal is sent from the ultrasonic oscillator 15 to the ultrasonic transmission sensor 17. Then, the signal from the ultrasonic reception sensor 17 is analyzed by the signal analyzer 21.
That is, data is acquired in two cases, the case where the sound absorbing material 25 is present and the case where the sound absorbing material 25 is absent.

After the analysis, the argon gas in the container 1 is discharged by the air / argon gas exhaust means 9. This is confirmed by the pressure gauge 33. Then, the container 1 is again filled with air. This is confirmed by the pressure gauge 33.
Necessary data can be acquired by the above operation. And the speed of the ultrasonic wave which passes the sound-absorbing material 25 in air and argon gas is each calculated.
Then, the physical properties of the sound absorbing material 25 are analyzed by a predetermined method based on the speed data.
The predetermined method is a method of analyzing by substituting four types of sound velocity data measured in two types of gas into an equation representing a wavelength constant of an ultrasonic band.

As described above, according to the present embodiment, the following effects can be obtained.
First, it becomes possible to easily measure the speed of sound of a desired ultrasonic wave in two different gas atmospheres, thereby enabling the physical properties of the sound absorbing material 25 to be easily and accurately analyzed. .
In particular, as the two different types of gases, those that can ensure a good S / N ratio (signal-to-noise ratio), specifically, air, acoustic impedance is larger than air, and kinematic viscosity is Since a certain gas 1.5 times or less that of air is selected and used, highly accurate data can be obtained.
In addition, physical property values such as “Tortuosity” and “Characteristic Length”, which have not been conventionally performed, can be easily analyzed, and thereby the relationship between the physical properties of the sound absorbing material 25 and the sound absorbing effect can be accurately clarified. As a result, it is possible to develop an effective sound absorbing material 25.
Further, a physical property value database of the sound absorbing material 25 which has not existed conventionally will be born.
And it becomes very useful also for development of the technique of estimating the acoustic characteristic of the sound-absorbing material 25 from the analyzed physical property value, and it is possible to shorten the development period and the development cost. It is also useful for the development of sound absorbing materials effective for noise countermeasures.

An example in which physical property values such as “Tortuality” and “Characteristic Length” are analyzed is shown.
First, the following physical property values could be obtained for the sound-absorbing material 25 having a density of 41.7 kg / m ³ .
Tortuity: 1.0124
Viscous Characteristic length
: 107.6 (μm)
Thermal Characteristic length
: 208.3 (μm)
Moreover, the following physical property values could be obtained for the sound absorbing material 25 having a density of 73.9 kg / m ³ .
Tortuity: 1.0288
Viscous Characteristic length
: 57.6 (μm)
Thermal Characteristic length
: 111.4 (μm)
Based on these physical property values, it becomes possible to analyze the flow resistance of the sound-absorbing material 25 and the sound absorption coefficient.

Next, a second embodiment of the present invention will be described with reference to FIG. In this case, the container 1 is first provided with an opening 1a as in the case of the first embodiment. However, in the case of the second embodiment, the opening 1a is always provided. It is open. Further, another opening 1b is formed at the bottom of the container 1, and an opening / closing lid 103 for discharging argon gas is attached to the opening 1b.
The other configurations are the same as those in the first embodiment, and the same parts are denoted by the same reference numerals and the description thereof is omitted.

  First, argon gas is supplied and filled into the container 1 by the argon gas supply means 5. Then, a desired measurement is performed. Next, by opening the opening / closing lid 103, argon gas having a specific gravity higher than that of air is automatically discharged and filled with air instead. Then, the same measurement is performed.

  Therefore, the same effect as in the case of the first embodiment can be obtained, and the configuration can be further simplified.

The present invention is not limited to the first and second embodiments shown in FIG.
First, as gas to be used other than air, for example, oxygen gas (O ₂ ), carbon dioxide gas (CO ₂ ), etc. can be considered in addition to argon gas (Ar).
The configuration of each other unit is an example and is not limited thereto.

  The present invention relates to an ultrasonic sound velocity measuring device, for example, efficiently measuring the sound velocity of an ultrasonic wave passing through a certain material such as a sound absorbing material, and thereby, the physical properties of a certain material such as a sound absorbing material. It is suitable when developing a new sound-absorbing material regarding what was devised so that it can be specified.

It is a figure which shows the 1st Embodiment of this invention, and is a perspective view which shows the structure of an ultrasonic sound speed measuring device. It is a figure which shows the 1st Embodiment of this invention and is a figure which shows the sound speed measurement result in the air. It is a figure which shows the 1st Embodiment of this invention and is a figure which shows the sound speed measurement result in argon gas. It is a figure which shows a comparative example, and is a figure which shows the sound speed measurement result in helium gas. It is a figure which shows the 2nd Embodiment of this invention, and is a perspective view which shows the structure of an ultrasonic sound speed measuring device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Container 3 Air introduction port 5 Argon gas supply means 7 Tube 9 Air and argon gas exhaust means 11 Tube 13 Ultrasonic transmission / reception means 23 Calculation means 25 Sound absorbing material 27 Material intrusion means 29 Sound absorbing material gripping part 31 Supporting part 33 Pressure gauge

Claims (7)

A container alternately filled with two different kinds of gases;
Material intruding means for causing a certain kind of material installed in the container to incend and descend with respect to a predetermined measurement position;
An ultrasonic transmission / reception means that is installed in the container and has an ultrasonic transmission sensor and an ultrasonic reception sensor disposed between the predetermined measurement positions;
Ultrasonic velocity calculating means for calculating the velocity of ultrasonic waves passing through the certain kind of material in the two different types of gas atmospheres based on the data obtained by the ultrasonic transmitting / receiving means;
An ultrasonic sound velocity measuring device comprising: In the ultrasonic sound velocity measuring device according to claim 1,
The two predetermined different gases are air and a gas having an acoustic impedance larger than that of air and having a kinematic viscosity not more than 1.5 times that of air. In the ultrasonic sound velocity measuring device according to claim 2,
The gas having an acoustic impedance larger than that of air and a kinematic viscosity of 1.5 times or less that of air is argon gas (Ar), oxygen gas (O ₂ ), or carbon dioxide gas (CO ₂ ). An ultrasonic sound velocity measuring device. In the ultrasonic sound velocity measuring device according to claim 1,
An ultrasonic sound velocity measuring apparatus, comprising gas supply / exhaust means for supplying / exhausting two predetermined different gases. In the ultrasonic sound velocity measuring device according to claim 4,
The gas supply / exhaust means comprises gas supply means for supplying the two different types of gases into the container, and gas exhaust means for exhausting the two different types of gases from the container. An ultrasonic sound velocity measuring device. In the ultrasonic sound velocity measuring device according to claim 1,
Fill the container alternately with the two different types of gases described above, and make the certain material appear and disappear at a predetermined measurement position in each atmosphere, and acquire data with and without a certain material. An ultrasonic sonic velocity measuring apparatus, wherein the ultrasonic velocity is calculated by the ultrasonic velocity calculating means based on data with and without a certain kind of material in each atmosphere. In the ultrasonic sound velocity measuring device according to claim 1,
The ultrasonic sound velocity measuring apparatus according to claim 1, wherein the certain material is a sound absorbing material.

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