JPH0549046B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ultrasonic wave transmitting/receiving device, and particularly to an ultrasonic wave transmitting/receiving device suitable for an ultrasonic flow rate measuring device.

[Conventional technology]

As a method of measuring flow rate in piping using ultrasonic waves,
Conventionally, there is a type shown in FIG. In the conventional example shown in FIG. 6, the ultrasonic waves output toward the downstream side from the harmonic transducer 51 of one ultrasonic transducer 50 follow propagation paths l ₁ , l ₂ , l ₃ , l ₄ , It reaches the ultrasonic transducer 61 of the other ultrasonic transducer 60 via _l5 and _l6 . Then, let t _d be the propagation time required in this case. Further, the ultrasonic waves outputted toward the upstream side from the ultrasonic transducer 61 of the other ultrasonic transducer 60 follow the propagation paths l ₆ , l ₅ , l ₄ , l ₃ , l ₂ , and l ₁ . Then, it reaches the ultrasonic transducer 51 of one of the ultrasonic transducers 50. The time required in this case is assumed to be t _u .

In this case, the flow velocity in the pipe 3 is determined by the following equation.

V=(C ² /2D·tanθ)·(t _u −t _d ) Here, D is the inner diameter of the pipe 3, θ is the refraction angle in the fluid, and C is the sound speed of the fluid.

As a result, if the sound velocity of the fluid is determined in advance, the flow velocity V of the fluid in the pipe 3 can be measured relatively easily based on the above equation,
At the same time, since the inner diameter of the pipe 3 is known, the flow rate of the fluid inside the pipe 3 can be determined very easily.

On the other hand, this conventional example has an essential drawback in that the flow velocity and flow rate in the pipe 3 cannot be measured if the sound velocity of the fluid to be measured is unknown. Therefore, by measuring the phase velocity and group velocity of the ultrasonic wave at the pipe wall portion during measurement of the pipe 3, the inventors have determined that even if the sound velocity of the liquid in the pipe 3 is unknown, We have developed a new method that makes it easy to calculate body flow velocity and flow rate.

[Problem that the invention seeks to solve]

However, in the ultrasonic transducers 50 and 60 shown in the conventional example described above, it is extremely difficult to measure the phase velocity of ultrasonic waves, especially in the wall portion of the pipe 3, and it is almost impossible. It has become a thing.

[Purpose of the invention]

It is an object of the present invention to provide an ultrasonic wave transmitting/receiving device which improves the disadvantages of the conventional example and can, in particular, very easily determine the phase velocity of ultrasonic waves in the pipe wall portion of a pipe when measuring flow velocity and flow rate. is its purpose.

[Means for solving problems]

The present invention includes a wedge member having an inclined surface and an ultrasonic emission surface, and an ultrasonic transducer fixed to the inclined surface of the wedge member, and an object to be measured that is brought into contact with the ultrasonic emission surface. In an ultrasonic transmitting/receiving device having a structure in which ultrasonic waves are obliquely incident on It has a sound wave reflecting surface. Then, a configuration is adopted in which a signal processing section is provided that calculates Cp of the ultrasonic wave of the wedge member based on the propagation time of the reflected ultrasonic wave from the reflecting surface. This aims to achieve the above-mentioned purpose.

[First Embodiment] Hereinafter, a first embodiment of the present invention will be described based on FIGS. 1 to 3.

In FIG. 1, an ultrasonic transducer 1 includes a wedge member 1A and an ultrasonic transducer 1B. The wedge member 1A has a trapezoidal cross section, and an ultrasonic transducer 1B is fixed to one slope 1a. Further, the other slope 1c is the ultrasonic transducer 1B.
This constitutes an ultrasonic reflecting surface that is perpendicular to the propagation path when the ultrasonic waves emitted from the wedge member 1A are reflected by the incident surface 1b and propagated within the wedge member 1A. Therefore, the internally reflected waves propagating through the wedge member 1A return to the ultrasonic transducer 1B side.

FIG. 2 is an explanatory diagram showing a case where the ultrasonic transducer 1 is incorporated into an actual ultrasonic flow rate measuring device. Here, the ultrasonic transducer 2 used is exactly the same as the ultrasonic transducer 1 described above.
That is, in FIG. 2, the reference numeral 1 indicates one ultrasonic transmitter installed on the upstream side of the pipe 3, and the reference numeral 2 indicates the other ultrasonic transducer installed on the downstream side of the pipe 3. show. Among them, one of the ultrasonic transducers 1 includes a wedge member 1A and a vibrator 1B for obliquely injecting ultrasonic waves into the piping 3, as shown in the figure.
It is equipped with In addition, the other ultrasonic transducer 2
The wedge member 2A and the vibrator 2B are also formed identically.
It is equipped with

Each of these ultrasonic transducers 1 and 2 is separately connected to a transmitting circuit section 11 and a receiving circuit section 12 via a transmitting/receiving switching section 10. In FIG. 2, a case is shown in which the liquid in the pipe 3 flows from the left to the right in the figure.

In each of the ultrasonic transducers 1 and 2, a signal as shown in FIG. 3 is repeatedly received depending on the flow velocity in the pipe 3.

In this figure 3, the wave of N=0 in figure 1 is
The received waves propagate in the order of paths l ₁ , l ₂ , l ₇ , l ₅ and l ₆ shown in FIG. 2 and reach the other ultrasonic transducer 2 without passing through the fluid. On the other hand, in the wave of N=0 in FIG. 2, the ultrasonic wave emitted from the ultrasonic transducer 2 propagates in the order of paths l ₆ , l ₅ , l ₇ , l ₂ and l ₁ shown in FIG. 2. , shows a received wave that reaches one of the ultrasonic transducers 1 without passing through the fluid, that is, an ultrasonic signal wave that propagates in the opposite direction through the same passage area.

In addition, the wave of N=2 in FIG.
It leaks once into the fluid 4 from the upper pipe wall portion of the pipe 3 in the figure, propagates through the fluid 4, and then leaks into the pipe section 3.
It enters the lower pipe wall of the piping section 3, propagates through the same pipe wall, leaks and propagates again into the fluid 4, enters the upper pipe wall of the piping section 3, and then passes through the upper pipe wall. The wave propagating and reaching the ultrasound transceiver 2 is shown. That is, a wave with N=2 indicates a received wave whose propagation path in the fluid is two. On the other hand, the wave N=2 in FIG. 3 represents a two-stroke received wave propagating in the opposite direction to the wave N=2 in FIG. 1.

Similarly, a wave with N=4 indicates a received wave whose path through the fluid is four strokes.

Among these, when ultrasonic waves are emitted from the upstream ultrasonic transducer 1 toward the downstream side, the propagation time t _d of each received wave received by the downstream ultrasonic transducer 2
(d=1, 2, 4, . . .) is expressed by the following equation in FIG.

t _d = [(L-ND・tanθ)/V _g ] + [(ND/cosθ)/(C+V・sinθ)] +τ ₁ +τ ₂ ... θ=sin ^-1 (C/V _p ) ... However, L: Interval between ultrasonic transducers N: Number of propagation steps in the fluid (N= for round trip)
2) V _g : Group velocity of the ultrasonic wave propagating in the piping section V _p : Phase velocity of the ultrasonic wave propagating in the piping section θ : Leakage propagation angle of the ultrasonic wave shown in Fig. 2 τ ₁ , τ ₂ : Ultrasonic wave propagation angle Time required to pass through the ultrasonic transducer On the other hand, when ultrasonic waves are reflected toward the upstream side from the ultrasonic transducer 2 on the downstream side, they are received by the ultrasonic transducer 1 on the upstream side. The total propagation time t _u (u
= 1, 3, 5, . . .) is expressed by the following equation similarly to the equation.

t _u = [(L-ND・tanθ)/V _g ] + [(ND/cosθ)/(C-V・sinθ)] +τ ₁ +τ ₂ ... However, L, N, V _g , X _P , θ and τ ₁ and τ ₂ are the same as in Eq.

These received waves are clocked by the clocking means 13 via the receiving circuit section 12 and the signal selection means 13A in the order of N=0, N=2, and N=4, and then sent to the signal processing section 20. It's becoming like that.

Next, the propagation time difference Δt _d and Δt _u of two received waves whose paths in the fluid differ by M distances is Δt _d = [(MD・tanθ)/V _g ] + [(MD/cosθ)/(C+V・sinθ)] ... Δt _u = (-MD・tanθ/V _g ) + [(MD/cosθ)/(CV・sinθ)] ... Here, in the case of M=2, the difference with Fig. 3 is In the relationship, Δt _d = 2t _d = t ₂ −t ₁ = t ₄ − _{t 2} Δt _u = 2t _u = t ₃ − _{t 1} = t ₅ − t _3From this equation, the sound speed C of the fluid is expressed as It can be calculated as the root of

f ₁ (V _p , V _g , Δt _u , Δt _d , C) = (1+αV _g ² )C ⁴ −(2V _p V _g +αV _p ² V _g ² )C ² V _p ² V _g ² =0... α=(Δt _u +Δt _d ) ² /4M ² D ² These calculations are performed in the signal processing section 20, and the results are displayed on the display means 18.

Using the data related to the sound speed C obtained by the formula, the phase velocity V _p and group velocity V _g of the ultrasonic wave in the pipe 3, and the two data Δt _d and Δt _u related to the propagation time difference, the signal processing unit 20 further calculates the following formula. calculation is performed.

V=f ₂ (V _p , V _g , Δt _u , Δt _d , C) = [V _p −(C ² /V _g )]・(Δt _u −Δt _d ) /(Δt _u +Δt _d ) ……′ As a result, the flow velocity of the fluid 4 in the pipe 3 is immediately calculated, and the result is sent to the display means 18. The display means 18 is adapted to convert and display this flow rate data as well as the flow rate data based on the flow rate data.

That is, the arrival time of each reception wave of N=0, 2 or N=2, 4 received by ultrasonic transducers 1 and 2 is measured, and the difference (for example, the time difference between N=0 and N=2) is calculated. By calculating, if the phase velocity V _p and group velocity V _g of the pipe wall of the pipe 3 are known, the sound velocity C of the fluid 4 in the pipe 3, as well as the flow velocity and flow rate can be immediately determined in real time. In addition, calculations can be displayed with high accuracy.

Here, the operating principle when determining the phase velocity V _p and group velocity V _g of the ultrasonic waves propagating through the pipe wall portion of the pipe 3 will be explained.

In FIG. 1, all of the internally reflected waves propagating within the wedge member 1A return to the ultrasonic transducer 1B. l ₁ and l ₁ ' indicate the propagation path and distance in that case. In this case, wedge member 1
By measuring the propagation time T ₀ of the ultrasonic wave inside A, the sound speed C _p inside the wedge member 1A can be calculated by the following equation.

C _p = 2 (l ₁ + l ₁ ') / T ₀ ... Also, there is a difference between the sound speed C _p of the wedge member 1A and the phase angle V _p of the ultrasonic wave propagating through the piping section 3 shown in Fig. 2. There is a relationship as shown below.

V _p = C _p /sin θ _i ... However, θ _i : Incident angle (see Fig. 1) Furthermore, as shown in Fig. 2, the distance between the ultrasonic incident points of the two ultrasonic transducers 1 and 2 is If the distance is L and the total propagation time is T when the ultrasonic wave emitted from the ultrasonic transducer 1B propagates through the pipe wall of the pipe 3 and reaches the ultrasonic transducer 2B, then the ultrasonic wave propagates through the pipe wall. The group velocity V _g of the ultrasonic wave is expressed by the following equation.

V _g = L/[T-T _p (l ₁ / (l ₁ + l ₁ ′))]... Here, since L, l, and l ₁ ′ are numerical values determined geometrically, the formula By measuring the propagation time T and T ₀ in and calculating the formula,
The required group velocity of the pipe wall portion of the pipe 3 can be calculated very easily. The calculation of the group velocity and phase velocity is also performed by the signal processing section 20.

[Second Embodiment] Next, a second embodiment will be described based on FIG. 4. In this second embodiment, a sound absorbing member 1E is attached to the other slope 1c of the first embodiment, and ultrasonic waves are placed at a position corresponding to the center of the ultrasonic waves arriving on the surface of the other slope 1c. It is equipped with a reflective member 1F. Reference numeral 1K indicates a case portion.

This has the advantage that a clearer first internally reflected wave can be obtained and the phase velocity can be measured more accurately.

In addition, in the one shown in FIG. 5, a receiving ultrasonic transducer 1R is attached to the other inclined surface 1c.
Even in this manner, the ultrasonic phase velocity of piping, etc. can be effectively measured.

〔Effect of the invention〕

Since the present invention is configured and functions as described above,
Sound velocity inside a wedge member that forms part of an ultrasonic receiver
It becomes possible to measure C _p with high precision in real time, and when using this, it is possible to measure the ultrasonic phase velocity of the pipe wall of the pipe (as mentioned above, this is necessary for calculating the flow rate) when measuring the flow rate, etc. It is possible to provide an unprecedented and excellent ultrasonic wave transmitting/receiving device that can extremely easily measure the temperature in real time and completely eliminates the need for temperature correction of measured values.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, and FIG.
Figures 3 to 3 are explanatory diagrams showing usage conditions, Figure 4 is a sectional view showing the second embodiment, Figure 5 is a sectional view showing an application example of Figure 4, and Figure 6 is a conventional example. It is an explanatory diagram. 1...Ultrasonic transducer, 1A...Wedge member,
1a... One inclined surface, 1B... Ultrasonic transducer,
1b... Ultrasonic emission surface, 1c... The other inclined surface as an ultrasonic reflecting surface, 20... Signal processing section.

Claims (1)

[Claims] 1. A wedge member having an inclined surface and an ultrasonic radiation surface, and an ultrasonic vibrator fixed to the inclined surface of the wedge member, the ultrasonic vibrator being in contact with the ultrasonic radiation surface. In an ultrasonic wave transmitting/receiving device having a structure in which ultrasonic waves are obliquely incident on an object to be measured, the ultrasonic wave component internally reflected by the ultrasonic emission surface is transmitted in the direction of propagation within the wedge member. The ultrasonic wave is characterized by being provided with an ultrasonic reflecting surface perpendicular to the direction of travel, and equipped with a signal processing unit that calculates the sound speed Cp of the ultrasonic wave in the wedge member based on the propagation time of the reflected ultrasonic wave from the reflecting surface. Sound wave transceiver device. 2. The signal processing section calculates the phase velocity Vp and group velocity Vg of the object to be measured, such as piping, with which the wedge member comes into contact based on the sound speed Cp of the ultrasonic wave of the wedge member calculated in the signal processing section. The ultrasonic wave transmitting/receiving device according to claim 1, further comprising a speed calculation function.