JPS63233334A - Method and apparatus for measuring sonic velocity - Google Patents

Abstract

PURPOSE:To remotely measure the sonic velocity of an object to be measured always present at high temp. and the change thereof with high accuracy, by measuring the phase speed and group speed in the ultrasonic wave used either one of ultrasonic wave guides and performing operation on the basis of the measured values according to a specific formula. CONSTITUTION:A pair of ultrasonic wave guides 1, 2 formed the same are opposed to each other so as to provide a definite distance therebetween and a medium to be measured is interposed between the mutual other end parts of the wave guides 1, 2 and, thereafter, the phase speed Vp and group speed Vg in the ultrasonic wave used in either one of the wave guides 1, 2 are measured. Next, almost simultaneously with measurement, the time before ultrasonic waves are propagated through the wave guides 1, 2 from one end parts thereof to the other end parts thereof and the ultrasonic waves leaked from the wave guides 1, 2 are received at one-end parts of the other wave guides 1, 2 at first through the medium to be measured and the time before the ultrasonic waves further leaked in the medium to be measured from the other wave guides 1, 2 reciprocally propagate between one wave guides 1, 2 to be received are measured to calculate the difference DELTAt between both times and, by performing an operation on the basis of these measured values according to formula, the sonic velocity V of the medium to be measured can be specified.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method and device for measuring the speed of sound, and in particular to a method for measuring the speed of sound that makes it possible to remotely measure the speed of sound in a fluid, etc. using leaky waves. and regarding its equipment.

[Conventional technology]

When measuring the sound speed of an object or measuring the temperature of an object using ultrasonic waves, a configuration is adopted in which longitudinal ultrasonic waves output from one ultrasonic sensor are directly propagated to the other ultrasonic sensor via the medium to be measured. There is.

The majority of methods attempt to measure the sound velocity or temperature and changes thereof based on the propagation time and changes thereof of the ultrasonic waves that are repeatedly transmitted and received during this period.

[Problems to be solved by the invention] Ultrasonic sensors used to monitor high-temperature fluids or fluids under dangerous conditions, or to monitor temperature changes in liquid hazardous materials, can be used even under these poor environments. It needs to be durable enough.

However, general ultrasonic sensors consist of a composite body of a vibrator and a protector, which are integrated with a bonding material, so there is an upper limit to the operating temperature (approximately 400 (t)), The situation was such that it was almost impossible to regularly and continuously measure temperatures in degrees Celsius. In addition, many vibrators and protectors are easily contaminated chemically, and there is a disadvantage that their deterioration progresses extremely quickly, especially in environments with rapid temperature changes.

[Purpose of the invention]

The present invention improves the disadvantages of the conventional example, and in particular, even if the objects to be measured, such as fluids or soft members, are harmful or constantly exposed to high temperatures, these objects can be To provide a method and device for measuring the speed of sound, which can remotely measure the speed of sound of an object and its changes with high precision, and can thereby measure the temperature, viscosity, and changes thereof of the object to be measured with high precision. That is its purpose.

[Means for solving problems]

Therefore, in the present invention, a pair of identically formed ultrasonic waveguides are opposed to each other at a certain distance, and a medium to be measured is interposed between the other ends of these ultrasonic waveguides, and then , measure the phase velocity Vq and group velocity Vq of the ultrasonic waves used in one or the other of the ultrasonic waveguides, and, before and after these measurements, from one end of the ultrasonic waveguide to the other end. The time it takes for the ultrasound to propagate and leak from the ultrasound waveguide through the medium to be measured until it is first received at one end of the other ultrasound waveguide, and the time for the ultrasound to leak from the ultrasound waveguide. Find the difference Δt between the time it takes for the ultrasonic wave that leaked into the medium to be measured to propagate back and forth between the ultrasonic waveguide and the one ultrasonic waveguide to be received, and based on these measured values, use the following formula. That is, by calculating F+ (Vp, Vp, Δt, V)=0, the sound velocity V of the medium to be measured is specified, thereby attempting to achieve the above object.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 7.

In Fig. 1, the sound velocity measuring device consists of a pair of plate-shaped (or band-shaped) ultrasonic waveguides (
1.2 (hereinafter simply referred to as "waveguide"), and an ultrasonic transducer 3.4 installed at one end of each waveguide 1.2.

In this embodiment, the waveguides 1 and 2 are made of stainless steel and have the same length. The other end of this waveguide 1.degree. 2 is disposed within a medium to be measured 5, as shown in the figure.

In this embodiment, one of the ultrasonic transducers 3.4 is used as a transmitter, and the other ultrasonic transducer 4 is used as a transfer device. Each of the wave transmitter 3 and the wave receiver 4 is attached to the side surface of one end of the waveguide 1.2. Then, an ultrasonic wave ('#1 wave) is obliquely incident on the waveguide 1 from the transmitter 3. The receiver 4 transmits the waveguide 2 under almost the same conditions as the transmitter 3.
It is now possible to receive ultrasound waves from

IA, 2A, IB, and 2B each indicate the end face of the waveguide 1.2 as an ultrasonic wave reflecting means.

Here, the waves propagating in the waveguides 1 and 2 and the propagation situation in the medium to be measured 5 will be explained.

When a waveguide comes into contact with a liquid or solid, a portion of the acoustic wave energy propagating through the waveguide tends to leak into the liquid or solid medium to be contacted. By utilizing this property, when a pair of waveguides is placed within the contacted medium, part of the energy of the sound wave propagating in one waveguide propagates to the other waveguide via the contacted medium.

At this time, the speed of sound in the contacted medium can be calculated by measuring the time required for the sound to propagate through the contacted medium.

When an ultrasonic wave is transmitted from the wave transmitter 3 to the waveguide 1, this wave propagates within the waveguide 1 toward the medium 5 to be measured. In this case, of the speed at which the ultrasound propagates through the waveguide 1,
Let the phase velocity be v21 and the group velocity be Vq. When the waveguide 1 is in contact with the medium 5 to be measured and the sound velocity V of the medium 5 at this time is smaller than the phase velocity vp of the waveguide 1, a part of the ultrasonic energy propagating in the waveguide 1 is transferred to the medium 5 to be measured. radiated into the medium 5. The radiation angle θ at this time is determined by the following equation.

θ-5in-' (V/Vq)
...... ■The ultrasonic wave that entered the medium 5 to be measured reaches the waveguide 2, and this waveguide! There are waves that propagate along a2 and waves that are reflected here and return to the medium 5 side. The wave that has traveled along the waveguide 2 is reflected at its tip 2A and reaches the transfer device 4.

Now, when the lengths of the two waveguides 1.2 are equal, and the interval between the waveguides is D, the arrival time of each received wave whose path in the medium to be measured is N steps is tN-((2L-NDtanθ )/Vq)+(ND/V
cos θ〕+τ1+τ! ”” ””■Here, τ1
．． τ8 is a fixed delay amount during transmission and reception.

Next, when calculating the difference in the case of N-1 and 3, Δt=2D ((1/Vcos θ)-(tan θ/
Vl) )・・・・・・■This formula■ and the above-mentioned formula■
From this, the following equation is obtained as an equation for determining the sound velocity (■) of the medium 5 to be measured.

F l (Vp, Vp, Δt, V) = (4D”
+VqTengthΔtz)v4-(8D" Vl, Vq+Vq"
Vq"Δt") V"+4D"Vq"Vq" Part ・・・・・・■ Therefore, if Δt is measured, the measured medium 5 can be calculated from equation 0 using this and the known D and Vq and Vq measured separately. Find the speed of sound V.

Here, the phase velocity Vq of the ultrasonic wave propagating in the waveguide 1 is
The operating principle when determining the group velocity Vq and the group velocity Vq will be explained.

First, FIG. 4 shows the wedge member 3A and the ultrasonic transducer 3B of the ultrasonic transducer 3. This wedge member 3A has a trapezoidal cross section, and an ultrasonic transducer 3B is fixed to one slope 3a. Further, the other slope 3c constitutes a surface perpendicular to the propagation path when the ultrasonic waves emitted from the ultrasonic transducer 3B are reflected by the incident surface 3b and propagated within the wedge member 3A. There is. Therefore, a portion of the internally reflected waves propagating within the wedge member 3A returns to the ultrasonic transducer 3B.

A'l+j'1' indicates the propagation path and distance in that case.

Therefore, by measuring the total propagation time T0 of the ultrasonic waves within the wedge member 3A at this time, the sound speed C2 within the wedge member 3A can be calculated by the following equation.

cp −2(z+ −1−J, ' ) /'re
・・・・・・■ Also, between the sound velocity C9 of the wedge member 3A and the phase velocity ■ of the ultrasonic wave propagating through the waveguide l,
There is a relationship as shown below.

Vp −Co /sin θ five
・・・・・・
・■ However, θ5: angle of incidence (see Figure 4) Furthermore, as shown in Figure 1, the length of the waveguide 1 is L,
Let T be the propagation time when the ultrasonic wave emitted from the ultrasonic transducer 3B propagates through the waveguide 1, is reflected at its tip, and reaches the ultrasonic transducer 3B, then the ultrasonic wave propagating through the waveguide 1 The group velocity Vq of is expressed by the following equation.

Vq=2L/T...
■It becomes. Here, since L is a fixed value, after all,
The required group velocity of the waveguide 1 can be easily calculated by measuring the total propagation time T at 20 and calculating the equation (2).

This calculation of the group velocity and phase velocity is performed by a first calculation section 13B of the signal processing section 20, which will be described later.

Here, to explain the signal processing system in more detail, the signal received by the receiving circuit section 12 is sent to the clocking means 13 via the signal selection means 13A, where the propagation time is clocked. Predetermined signal processing is performed in the processing section 20. This signal processing section 20 has a first memory 14 as shown in FIG.

It has a time difference calculation means 15, a second memory 16 as a storage means, and a second calculation section 17, and further includes a time difference calculation means 15.
The configuration includes a first arithmetic unit 13B between the second memory 16 and the second memory 16. This signal processing section 20 calculates the phase velocity V21 of the waveguide 1 (or 2), the group velocity Vq, and the sound velocity (2) of the medium to be measured. The calculation results in the signal processing section 20 are displayed on the display means 18.

Each electrical system, such as the signal processing section 20 and the above-mentioned time measuring means 13, is driven and controlled by a main control section 30, respectively.

This main control unit 30 outputs an overall drive control signal for synchronizing the operation timing of the entire circuit, and also has a first control function to obtain the ultrasonic phase velocity in the waveguide 1 or 2 during measurement. Similarly, it has a second control function for determining the ultrasonic group velocity of the waveguide 1 or 2, and a third control function for determining the sound velocity of the medium to be measured. In this embodiment, these control functions of the main control section 30 can be switched by an external command from an operator using a measurement condition setting section 30A.

Next, the overall operation of the above embodiment will be explained.

First, waveguides 1 and 2 and ultrasonic transducers 3 and 4 are arranged in the medium to be measured as shown in FIG. Subsequently, when the entire apparatus is operated, a received waveform shown in FIG. 2 or 3 is obtained on the receiving side.

Among these, the waveform shown in Fig. 2 is the waveform obtained when the ultrasonic transducer 4 is electrically separated and only one ultrasonic transducer 3 performs the transmitting operation and the receiving operation. A waveform obtained when wave path 2 is used as a reflecting member is shown. Here, TR indicates a transmitted wave, and RE indicates a received wave. Among the received waves RE, W is the reflection surface 3 in the ultrasonic transducer 3
Wt indicates the transfer that has been reflected at C, and Wt indicates the transfer that has been reflected twice at the reflection surface 3C in the ultrasonic transducer 3.

Further, N-2 indicates a delivery wave that has passed through the path in the medium to be measured for two strokes, and N=4 indicates a received wave that has similarly passed through a four-stroke path. The mark * indicates the reception of the wave delayed by the time required for one round trip through the waveguide 1 after the wave of N=2 was received.

3 shows a waveform obtained when the ultrasonic transducer 3 is used as a transmitter and the ultrasonic transducer 4 is used as a transfer device. Here, N=1 indicates a received wave that has passed through the medium path for only one journey, and N=3 indicates a received wave that has similarly passed through three routes. Further, the mark * indicates a received wave delayed by the time required for making one round trip through the waveguide 2 after the N-1 wave is received.

For N=1 received waves, there are the following two propagation paths. In the first propagation path, the leaked ultrasonic wave propagates toward the other end of the waveguide 1 and propagates to the waveguide 2.
This is the case when it is reflected at the other end and reaches the ultrasonic transducer 4.

The second propagation path is such that the ultrasonic wave reflected at the other end of the waveguide 1 leaks into the medium to be measured on the way back to the ultrasonic transducer 3 and propagates to the waveguide 2, causing the ultrasonic wave to be transmitted and received. This is the case when it reaches vessel 4.

The propagation time is the same in both cases.

Next, the first control function of the main control unit 30 is activated, and the entire circuit is set to a measurement state (phase velocity measurement mode) of the phase velocity Vq of the waveguide 1 (or 2) portion at the time of measurement. Once the entire circuit is set to this phase velocity measurement mode,
The other ultrasonic transducer 4 is electrically disconnected from the transmission/reception switching unit 10, and the setting is such that only one ultrasonic transducer 3 can perform transmission and reception operations (in this case, the A transducer 4 may be used instead of the transducer 3). FIG. 5 shows the transmission state of the transmitting and receiving signals in this case. The transmitting signal TR transmitted from the transmitting circuit section 11 is simultaneously sent to the ultrasonic transducer 3 and the receiving circuit section 12. The internally reflected wave RE from the wave transmitter 3 is also sent to the receiving circuit section 12. These signals TR and RE are selected by the signal selection means 13A.
The data is sent to the timer 13, where the above-mentioned time T0 (7'0x j , -it) is measured, and the time data is sent to the first calculation unit 13B. 1st
In the calculation section 13B, calculations of 2 and 2 are performed based on the measurement time T0, and the results are stored in the second memory 16 and displayed on the display means 18.

Next, when the operator activates the second control function of the main control section 30, the entire circuit is set to the group velocity measurement mode of the waveguide 1.

In this case, in this embodiment, one ultrasonic transducer 3 performs a transmitting operation, and the other ultrasonic transducer 4 performs a receiving operation.

That is, the transmission signal TR and reception signal RE are transmitted as shown in FIG. These signals TR and RE pass through the signal selection means 13A (the signal selection means selects N-1 and the signal marked with *) and are sent to the timekeeping means 13A, where they are sent to the timer means 13A, where they are sent for the time T (where T= t3) is measured as the arrival time difference between N-1 and the received signal marked with *, and the time data is sent to the first calculation unit 1.
Sent to 3B. In the first calculation section 13B, the calculation of equation (2) is performed based on the measurement time T, and the group velocity Vq obtained thereby is stored in the same manner as the phase velocity vp, and similarly displayed on the display means 18. It looks like this.

Next, the main control unit 3 is activated by input commands from the operator.
When the third control function No. 0 is activated, the entire circuit is set to the sound speed measurement mode of the medium to be measured. In this sound velocity measurement mode of the medium to be measured, the signal selection means 13A allows the received waves of N=1 and N-3 in FIG.

The clock means 13 clocks the propagation time of the two input signals and then sequentially sends the time data to the first memory 14. When the first memory 14 receives N=3 time data, it outputs it to the time difference calculation means 15 together with N-1 time data.

This time difference calculation means 15 immediately calculates the time difference Δt (here, Δ1-14) and stores it in the second memory 16.

When this Δt is input, the second memory 16 outputs the phase velocity Vq and group velocity Vq of the ultrasonic wave of the waveguide 1, which are stored in advance together with them, to the second calculation unit 17. This second calculation unit 17 calculates the formula (■) based on these input information, and the sound velocity of the medium to be measured (■) obtained as a result is
is output to the display means 18 and displayed in real time.

Next, specific experimental results in the above embodiment will be explained based on FIGS. 8 to 11.

In the experimental model shown in Fig. 8, steel plates with a thickness of 0.95 (m) are used as waveguides 1 and 2, and a variable angle probe with a frequency of 1 (MH, ) is used as an ultrasonic transducer. I used 33.34. The wedge of the variable angle probe is made of acrylic resin, the incident angle is fixed at 31.5 degrees, and the S
The 0 mode plate wave is guided. Tap water (21 [°C]) was used as the medium to be measured. Therefore, in this case, the group velocity Vq and phase velocity ■ of the guided wave can be considered to be approximately equal to the S0 mode even within the measured medium 5 (1,
^.

Viktrov, rRayleigh and La
l1b Waves J P, 117).

The applied electric pulse was a two-sine wave of 200 (V□). An example of the observed received waveform is shown in Figure 9. In the figure,
T indicates the waveform of the transmitter, and R indicates the received waveform of the receiver. N = 1.3 indicates a wave whose underwater path is 1 stroke and 3 strokes, respectively. The water mark indicates a wave of N-1 further passes through waveguide 2 by 1 stroke.
This shows the received waveform of the wave that went back and forth. In this example, Δt = 75
．． 1 (#8), the group velocity of the waveguide 2 in the ultrasonic wave used is experimentally determined from the arrival time difference between the wave marked * and the wave N-1, and is given as v,=5200 (,/,). f.

In addition, the phase velocity can be calculated from the acoustic velocity of the acrylic, 2720 (,/,), and the set incident angle of the variable angle probe, 31.5°C.
Vj =5300 (,/,).

On the other hand, the relationship of equation 0 was confirmed by actual measurements while changing the spacing between waveguides 1 and 2, and the results are shown in FIG. 1o. From this, it was possible to obtain Δt/D −1,26 (n/m). The sound velocity V of water can be calculated from Equation 0 using Vq and Vq obtained previously. The results are shown in FIG. The temperature is 3
The points were taken and measured. The results are in very good agreement with publicly available values.

In this way, according to this embodiment, the sound velocity V of the medium to be measured can be effectively determined regardless of the lengths of the waveguides 1 and 2, and the In addition to detecting the time difference, the phase velocity v of the waveguide 1 is detected before and after this.
2 and the group velocity Vq can be measured at the same time. Therefore, the sound velocity (2) of the medium to be measured 5 can be immediately determined without immersing the ultrasonic transducers 3 and 4 into the medium to be measured. Since the length of 1 and 2 is unrelated,
For example, it is possible to remotely measure high-temperature fluids or highly dangerous fluids, and therefore, even if a normal ultrasonic transducer 3 is used, sufficient durability can be ensured. . Furthermore, if the insertion dimensions of the waveguides 1 and 2 into the medium to be measured 5 are set large, the receiving sensitivity will increase, but this has no direct relation to the measurement accuracy. The dimensions of the ultrasonic sensor device to be inserted into the ultrasonic sensor device are not required to be particularly precise, and therefore, it is possible to obtain an ultrasonic sensor device with excellent properties as a remote measurement device, which is extremely easy to handle.

Furthermore, since the insertion dimensions into the medium 5 to be measured are directly related to the level of the ultrasonic waves received by the ultrasonic transducer 3, the liquid level of the medium 5 to be measured can be detected at the same time. There are also advantages.

Further, in the above embodiments, the waveguide is formed by a plate-shaped member, but the waveguide may be formed by other members 1, such as a round bar member, a suitable wire member, a pipe-shaped member, etc. good.

In addition, in the above embodiment, when measuring the group velocity Vq of the waveguide 1, the case where t measured in FIG. In addition, when measuring Δt, the case shown in FIG. 3 was illustrated in the above embodiment, but after obtaining the received signal shown in FIG. 2 under the configuration shown in FIG. t4 (however, 14=Δt) may be used. Further, in the above embodiment, the case where the phase velocity vp and the group velocity (2) of the ultrasonic wave in the waveguide 1 are determined prior to the measurement of Δt was exemplified, but these may be performed in the reverse order.

Furthermore, in the above embodiment, the first . Although the case where the second and third control functions operate is illustrated, these control functions may operate automatically one after another. In addition, since it is possible to measure the sound velocity of a liquid with high precision, if the relationship between temperature and sound velocity is known in detail, such as in water, the corresponding temperature change in the liquid can also be measured with high precision. be able to.

〔Effect of the invention〕

Since the present invention is configured and functions as described above, it is possible to measure the sound speed of a medium to be measured with high accuracy regardless of the length of the waveguide, and the speed of sound in the medium to be measured can be measured with high accuracy, for example. Even with high-temperature fluids or highly dangerous fluids, remote measurement is fully possible from a distance, and even if the phase velocity and group velocity of the waveguide are unknown, they can be measured simultaneously, making calculations easier. To provide an unprecedented and excellent method for measuring the speed of sound and its device, capable of performing high-precision sound speed measurements that do not require any temperature correction by calculating the speed of sound after measuring all necessary variables in real time. be able to.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram showing one embodiment of the present invention, FIGS. 2 and 3 are explanatory diagrams showing an example of the transmitted waveform and received waveform in FIG. 1, respectively, and FIG. 4 is the same as that shown in FIG. 1. A partially omitted sectional view showing the ultrasonic transducer used, FIGS. 5 to 7 are operation explanatory diagrams of FIG. 1, and FIGS. 8 to 1.
FIG. 1 is an explanatory diagram showing experimental examples, and FIG. 12 is an overall configuration diagram showing another example. 1.2... Ultrasonic waveguide, IA, 2A, IB. 2B... Ultrasonic reflecting means, 3, 4...
Ultrasonic transducer, 10... Transmission/reception switching unit, 1■
..... Transmission circuit section, 12 ..... Receiving circuit section, 13 ..... Time measurement means, 13A ..... Signal selection means, 15 ..... Time difference Calculation means, 16...
...Second memory as storage means, 17...
...Second calculation unit as sound velocity calculation means. Patent applicant: Ken Ken Nakabachi (one idiot) Figure 1 Figure 2 - Figure 4 Figure 5 Figure 6 Figure 7 Figure 1O

[μS]

Figure 11

Claims (2)

[Claims] (1) A pair of identically formed ultrasonic waveguides are opposed to each other at a certain distance, and a medium to be measured is interposed between the other ends of these ultrasonic waveguides, and then the The phase velocity V_p and group velocity V_q of the ultrasonic wave used in one or the other ultrasonic waveguide are measured, and before and after these measurements, the ultrasonic wave is applied from one end of the ultrasonic waveguide to the other end. At the same time, the time required for the ultrasonic wave leaked from the ultrasonic waveguide to be first received at one end of the other ultrasonic waveguide via the medium to be measured, and the time from which the ultrasonic wave leaked from the other ultrasonic waveguide Furthermore, the difference Δt between the time it takes for the ultrasonic wave leaked into the medium to be measured to propagate back and forth between the one ultrasonic waveguide and the time it is received is calculated, and based on these measured values, the following formula is used. That is, a sound speed measuring method characterized in that the sound speed V of the medium to be measured is determined by calculating F_1(V_p, V_q, Δt, V)=0. (2) a pair of ultrasonic waveguides each equipped with an ultrasonic transducer at one end and an ultrasonic reflecting means at the other end disposed within the medium to be measured; Each of the devices has a transmitting/receiving switching section that alternately switches and connects the transmitting circuit section and the receiving circuit section as necessary, and the ultrasonic wave leaking from one of the waveguides to the other is transmitted to the receiving circuit section. The time it takes for the ultrasonic wave to propagate in the medium to be measured and be received by the ultrasonic transducer of the other ultrasonic waveguide, and the ultrasonic wave leaked from the other ultrasonic waveguide into the medium to be measured. and a time difference calculation means for calculating the arrival time difference between the two received waves measured by the time measurement means. , a storage means for storing the output of the time difference calculation means, and the storage means measures and stores the phase velocity and group velocity of the ultrasonic wave used at the time of measuring the sound velocity of the waveguide, and the storage means 1. A sound speed measuring device characterized by further comprising a sound speed calculation means for calculating the sound speed of the medium to be measured by performing a predetermined calculation based on the output information of the sound speed measuring device.