JP2000258212A - Method and apparatus for measuring flow velocity in open channel and calibration inspecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply measure the flow velocity and the flow rate at high accuracy, utilizing the deflection phenomenon appearing during propagating of an ultrasonic wave in water. SOLUTION: A transmitting transducer 1 is disposed in one end of on a virtual measuring straight line B of an open channel, a pair of receiving transducers 2 with a remove d are disposed perpendicularly to the virtual line B. The receiving transducers 2 (21, 22) are displaced or the transmitting transducer 1 is turned, the pair of receiving transducers 2 receive an ultrasonic wave to provide output signals, the deflection distance 1 is obtained from the time when these output signals are equal in magnitude or the turn angle of the turned transducer 1 is obtained as a deflection angle, thereby calculating the flow velocity in the open channel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique used to ultrasonically measure the horizontal average flow velocity at one or more water depths for measuring flow in rivers and large artificial open channels. .

[0002]

2. Description of the Related Art As is well known, a typical method for measuring the flow rate at a predetermined location in an open channel such as a river is to measure a cross-sectional area at a predetermined location and a flow velocity of a fluid at the cross-sectional portion. It is known that the imaginary line along the width of the open channel is divided into several sections at predetermined intervals, and various means are provided at the center of each section. Measure the local flow velocity at the vertical water depth position using, for example, a propeller type current meter, calculate the average flow velocity on this vertical line, obtain the partial flow rate for each divided section from the product with the partial cross-sectional area, and calculate the sum of them Was done from

The details of the above conventional means are described in "Flow velocity measuring apparatus" in Japanese Patent No. 2863748 previously proposed by the present inventor and the applicant, or in "River flow rate measuring apparatus and apparatus" in Japanese Patent Application Laid-Open No. 9-196727. The method has been clarified in the conventional description.

[0004] The proposed invention measures the flow velocity by utilizing the fact that the propagation time required for an ultrasonic wave transmitted into water from a certain fixed point to reach another certain fixed point varies with the flow velocity. Apparatus and method. The flow velocity measuring means using this ultrasonic wave does not disturb the flow velocity distribution and has linearity from a fine flow velocity to a high flow velocity, as compared with the mechanical and local measuring means as described above, which is mainly used conventionally. Real-time measurement of flow rate is possible, knowing the flow velocity component,
The advantages are that continuous automatic observation is possible, and maintenance is easy because there is no mechanical operation part.

The basic flow velocity measuring means using ultrasonic waves will be described with reference to FIG. 11 and the following formulas. In order to measure the flow rate in an open channel such as a river, at least one kind of ultrasonic flow is used. The method of measuring the horizontal average flow velocity at the water depth is as follows.

As shown in the cross section of FIG.
Depending on the water depth, some
A transducer (ultrasonic transducer)₁ And B₁ , A_Two And B_Two 
.., Etc., facing each other one by one,
Form a fixed angle φ with respect to the water flow direction as shown in the plan view
So that the transducer A₁Or
Transmits ultrasonic waves from the transducer B₁ When you reach
Interval t_ABAnd conversely, transducer B₁ Super sent from
Sound wave is transducer A₁ Time t to reach _BAMeasure
Then, time t_ABAnd time t_BAAre the equations (a) and (b)
From this equation (a) and (b), the difference Δt
= T_BA-T_ABIs given by equation (c).
The speed V is given by equation (d). Where c is the speed of sound in river water
V is the horizontal average flow velocity and L is a pair of transducers.
This is the distance between A and B.

[0007]

(Equation 1)

The square of sound velocity c ² is substantially the equation (e) from the product of the equations (a) and (b), and if this is substituted into the equation (d), the most frequently used flow velocity measurement equation ( f). This flow velocity measurement formula (f) is used to calculate the ultrasonic propagation time difference (transit time d
iffrence) method. The equation (g) is also used for the flow rate measurement equation, but it is finally the equation (f '), which is the same.

[0009]

(Equation 2)

In addition to an open channel, an ultrasonic flowmeter for a closed channel (for example, a pipe), which is currently most widely known, measures the flow velocity by the ultrasonic propagation time difference method. In addition to this method, there are a frequency difference method, a phase difference method, and the like. In any case, the ultrasonic wave propagation time difference method is used, and the paired transducers are fixed with respect to the flow velocity V as in FIG. They are arranged at an angle φ.

[0011]

However, the following problems occur when trying to measure the horizontal average flow velocity in a wide river by such a conventional technique.

The first problem is that, in order to calculate the flow rate by measuring the horizontal average flow velocity (at various water depths), it is necessary to select the cross section S of the flow perpendicular to the flow of the water. The point is that the selection of the cross-sectional area S corresponding to the measured horizontal average flow velocity is uncertain and cannot be determined.

To obtain the flow rate Q, the horizontal average flow velocity V _i at various water depths is measured, and the total average flow velocity V _S orthogonal to the cross section S is determined.
Calculating a, to some methods for obtaining the formula (h), or by measuring the horizontal average flow velocity V _i, Q from the sum of the partial flow rate multiplied by V _i in the partial cross-sectional area S _i as in equation (i) There is also a way to ask. (FIG. 11).

[0014]

(Equation 3)

Here, the ultrasonic wave is affected by the flow velocity,
Although it propagates along the line, the flow velocity at each point on the L line has various values depending on the open channel form balanced with this point. No matter which of the above methods is used, the cross section in the section D = Lcosφ of the river where the ultrasonic wave propagates is shown in FIG.
As is clear from the explanatory diagram in which the plane and the cross section shown in FIG. 2 are synthesized, not only the river width but also the depth and depth of the riverbed are not the same but various. I do not know clearly that it is compatible with. Therefore, the cross-sectional area S at an arbitrary point in the section D is selected, and as a result, the measurement error of the flow rate is clearly increased.

For example, when the river width B is 500 m and φ = 45 °
Then D = 500m, but there will be few natural rivers with the same river cross section in the entire section of D = 500m. Figure 1 above
As shown in Fig. 2, it should be varied depending on the depth and unevenness of the riverbed, and only a part of the artificial artificial open channel is the exception.

The second problem is caused by the development of a diagonal flow velocity component in a river. As shown in FIG. 13, the flow velocity V that must be measured in order to calculate an accurate flow rate is a right-angle flow velocity component V _直 perpendicular to the cross section S. If the direction of the flow velocity coincides with a right angle velocity components V _⊥, if an angle of the L-lines and phi, the flow velocity V measured by conventional techniques such as time difference method is a right angle velocity components V _⊥, In the case of a mixed flow in which the direction of the flow velocity forms an angle of φ + α with the L line, the flow velocity V calculated by the equation (f) is a true right-angle flow velocity component V _⊥
In this case, the measurement error of _V⊥ becomes large. Therefore, in the above-mentioned case, the flow velocity V is first determined by the equation (j), and then the right-angle flow velocity component V _⊥ is calculated by the equation (k) in consideration of the influence of the mixed flow angle α caused by the conventional technique. It is.

[0018]

(Equation 4)

As described above, although the actual flow velocity V _{す る} for measuring the flow rate is expressed by the equation (k), the conventional technique cannot know the actual oblique flow angle α. ), The flow velocity V ′ is calculated by the equation (1), and the flow velocity V ′ is set to _V⊥. Therefore, the measurement error δ _V of the flow velocity _V⊥ is represented by the equation (m).

If φ = 45 °, tan φ = 1, so that the measurement error δ _V = −tan α. Angle of mixed flow is α = 1 ° -10
In the range of °, δ _{V is} 1.75 to 17.63%. Since α = 2 ° to 3 ° is common in natural rivers, it is normal that δ _V = 3.5 to 5.2%, and such an error is a problem.

The third problem is a problem that occurs due to the use of ultrasonic pulses. First, a transducer cannot transmit an ultrasonic wave by one complete pulse like a square wave, for example, due to its principle.
(A) As shown in the figure on the left, the amplitude gradually increases in the first 3 to 4 waves, becomes a maximum, and then gradually attenuates and converges with several waves. Sound waves are emitted. A radio pulse as shown in the left diagram of FIG. 14B cannot be transmitted.

Therefore, the moment when the above-mentioned transducer receives a pulse is usually when the output signal of the transducer which has received the ultrasonic wave reaches a certain level (check level, CL). Since it is used as a reference, it is detected as the reception instant only when the wave reaches this level, and the time difference between the reception instant and the emission instant is defined as the ultrasonic propagation time.

However, the ultrasonic pulse is attenuated by propagation in water. This is because the transmitted pulse is a shock wave and the frequency spectrum band is wide, so that when the ultrasonic wave propagates in water, the high frequency (higher har
monic) Because the component decays quickly, the bell-shaped pulse is
4 (a) As shown in the right figure, the fundamental wave is greatly attenuated as the pulse shape changes. Even if an ideal radio pulse can be transmitted, an attenuated and deformed sound wave is eventually received as shown in the right diagram of FIG. 14B.

When the amplitude of the bell-shaped pulse changes, FIG.
As clarified in (c), when checking the instant of reception, an error of about one to two cycles of ultrasonic waves generally occurs. This is because when the bell-shaped pulse is attenuated, the wave reaching the check level (CL) shifts.

When an ultrasonic pulse is received and amplified, a wide band amplifier is used so that the waveform of the pulse is not distorted. Therefore, noise is also amplified over a wide spectrum, and especially the pulse shape is increased. There is a risk that the noise will be amplified with high efficiency and reach the check level, which will confuse the ultrasound transit time measurement.

Furthermore, the distance L between the pair of transducers is long, or the fluid flow has various overcurrents (vortex, ed).
If dy) occurs, the concentration of suspended particles changes, or if there is a boundary between the concentration of suspended particles and the water temperature, the refraction diffusivity and absorption attenuation of the ultrasonic pulse will change significantly. Ultrasonic intensity (sound pressure) pulsates violently instantaneously. For this reason, it is difficult to check the moment when the ultrasonic wave is received (arrived), and there is a case where the measurement error of the ultrasonic wave propagation time becomes large, or the measurement becomes impossible because all the waves do not reach the check level. .

That is, as described above, the receiving transducer
Since the instant of reception is determined based on the time when the output signal of the sensor reaches a certain level (CL), as shown in FIG. An error of about 1 to 2 cycles of the ultrasonic wave is generated depending on whether or not (CL) is reached. The cause of the error is caused by the above-mentioned macro overflow, suspended particles, suspended particle concentration, water temperature boundary, and the like. The pulsation of ultrasonic intensity (sound pressure) is mentioned.

Conversely, if the output signal of the receiving transducer is over-amplified, a wave that should not be checked reaches the check level and is detected about one to two cycles earlier, or even irrelevant noise is detected. This causes an inconvenience of reaching the check level and being regarded as the reception moment. This limits the size of rivers and the state of flowing water where the ultrasonic propagation time difference velocity measurement method can be used.

In the prior art, these three main problems make it difficult to measure the horizontal average flow velocity in a wide natural river, and even if it is measured, the error is likely to be large. There is hardly any example of measuring by using ultrasonic waves. The only thing that is used is the artificial open channel, which is relatively narrow, has a constant cross section, and has a uniform and stable water flow.

As described above, the ultrasonic propagation time difference method including the frequency difference method, the phase difference method, etc., as a means for measuring the flow velocity, requires the water at any point to calculate the flow rate. The cross section S of the flowing water perpendicular to the flow must be selected, but the cross section S corresponding to the average velocity to be measured
Is uncertain and cannot be selected, resulting in large flow rate measurement errors, river flow errors due to the development of mixed flow components, and attenuation due to the use of ultrasonic pulses that are bell-shaped and contain many high-frequency components It is difficult to guarantee the receiving strength, and it causes a measurement error of the propagation time, and furthermore, the pulsation of the attenuation causes the measurement error of the propagation time. .

Therefore, as a means for solving this drawback,
Attention is paid to utilizing the deflection phenomenon that occurs when ultrasonic waves propagate in water. In other words, this deflection phenomenon means that when a continuous wave (sine wave) of ultrasonic waves propagates underwater along the flow measurement cross section, the water, which is the propagation medium, moves at a certain flow velocity, so that it is immovable on the riverbank. This is a phenomenon in which the point at which the ultrasonic wave reaches is a point away from the point at which water does not flow in the direction of flow velocity.

Accordingly, the present invention has been developed in order to solve the above-mentioned dissatisfaction points of the prior art, and utilizes a deflection phenomenon generated when an ultrasonic wave propagates in water to easily and accurately adjust a flow velocity and a flow rate. The purpose is to be able to measure.

[0033]

According to a first aspect of the present invention, there is provided an ultrasonic flow velocity measuring method for measuring a flow velocity in an open channel, the method comprising measuring an arbitrary flow rate substantially perpendicular to the open channel. The intersection point of the virtual measurement straight line B with the other end of the open channel is set as the origin a, and the transmitting transducer part is arranged within one end of the virtual measurement straight line B of the open channel, and the other end is set. And a pair of receiving transducer sections spaced at a distance d in a direction perpendicular to the virtual measurement line B, and displacing at least one of the reception transducer sections in a direction perpendicular to the virtual measurement line B. Each of the pair of receiving transducer units receives an ultrasonic wave transmitted from the transmitting transducer unit with the directional characteristic centered toward the origin a, and at a position where the magnitude of the output signal becomes equal. The center of the directional characteristics of the ultrasonic wave is the measurement point b. Then, a deflection distance 1 (small el) is obtained from the distance between the measurement point b and the origin a, and the deflection distance 1 and the ultrasonic wave reach the reception transducer section from the transmission transducer section. T or the deflection distance l, the sound velocity c of the ultrasonic wave, and the virtual measurement linear distance B
The flow velocity of the open channel is calculated from the value of (1).

The ultrasonic wave transmitted by the transmitting transducer portion from one end on the virtual measurement straight line B of the open channel with the center of the directivity characteristic directed toward the origin a is generated when the ultrasonic wave propagates in the water which is a fluid. Due to the deflection phenomenon, it reaches a certain point downstream of the origin a at the other end of the open channel.

In this case, since at least one of the receiving transducer sections is displaced in a direction orthogonal to the virtual measurement line B, the magnitudes of the reception output signals U ₂₁ and U _{22 of the} pair of receiving transducer sections are obtained. The arrival point at the center of the directional characteristics of the ultrasonic waves transmitted from the transmitting transducer unit can be grasped from the positions of the two receiving transducer units at the time (points) at which the two are equal to each other. With this point as the measurement point b, the deflection distance 1 between the point a and the origin a is determined.

Therefore, the obtained deflection distance 1 and the time t until the ultrasonic wave reaches the receiving transducer unit from the transmitting transducer unit, or the deflection distance 1 and the sound speed c of the ultrasonic wave, are virtually measured. Using the value of the linear distance B, the flow velocity in the open channel can be calculated.

An ultrasonic flow velocity measuring method according to a second aspect of the present invention is a method for measuring the flow velocity of an open channel, wherein an arbitrary virtual measurement line B substantially orthogonal to the open channel is connected to the other end of the open channel. The intersection point is set as the origin a, and the transmitting transducer part is arranged in one end on the virtual measurement line B of the open channel, and the distance d in the direction perpendicular to the virtual measurement line B in the other end. Are arranged at positions where the magnitudes of the respective output signals become equal when the center of the directional characteristic of the ultrasonic wave reaches the origin a, and the transmitting transducer section is formed. Is rotated, each of the pair of receiving transducer units receives the ultrasonic wave transmitted by the transmitting transducer unit, and transmits the ultrasonic wave to the virtual measurement line B when the magnitudes of the output signals are equal. The rotation angle of the transducer is defined as the deflection angle θ. From the value of the deflection angle θ and the ultrasonic speed of sound c, characterized by calculating the flow velocity of the open channel.

Therefore, when the velocity of the ultrasonic wave transmitted from the transmitting transducer portion is V ≠ 0, the other side of the open channel downstream from the transmitting direction due to a deflection phenomenon generated when the ultrasonic wave propagates in the water which is a fluid. When the transmitting transducer section is rotated from the direction of the virtual measurement straight line B so that the reaching point coincides with the origin point a, that is, the output signal becomes equal, a certain point at the end is reached. The moving angle can be obtained as the deflection angle θ, and the flow velocity in the open channel can be calculated using the deflection angle θ and the value of the sound speed c of the ultrasonic wave.

Next, an ultrasonic flow velocity measuring method according to a third aspect is directed to the first and second aspects of the present invention.
The respective outputs of the differential section are input to the differential amplifier, and from the position where the output signal of the differential amplifier becomes ΔU = 0, the measurement point b, or from the rotation angle at which the output signal of the differential amplifier becomes ΔU = 0 Obtain the deflection angle θ.

According to the present invention, as described above, each of the pair of receiving transducer units receives the ultrasonic wave, and the point in time at which the magnitude of the output signal with respect to the position movement and the change in the rotation angle becomes equal (point). The magnitude comparison for this purpose is somewhat easier if both are amplified, but in order to amplify with exactly the same amplification degree and to compare the magnitudes of any two different signals each time, It takes time and effort.

Therefore, a differential amplifier is used. First of all, since the difference between the two signals is output as one signal, it is not necessary to compare the magnitudes of the two signals in order to search for an equal position or angle. Then, the deflection distance l or the deflection angle θ may be obtained from the position at that time. Next, if the amplification is large, it becomes possible to check the output near zero very precisely and easily. In this case, however, it is not necessary to amplify both of them, so that the above-described error due to the unequal amplification degree is caused. It cannot occur. Since the point to be determined is zero, even if the amplification degree fluctuates at the moment, for example, zero is always zero.

A fourth aspect of the present invention is directed to an ultrasonic flow velocity measuring method according to the first or second aspect, wherein the reception output signal of one of the receiving transducer units is U ₁ , and the other receiving transducer is U ₁ . The reception output signal of the unit is U _2, and the position of the other receiving transducer unit at which U ₂ / U ₁ is maximum or U ₁ / U ₂ is minimum is measured point b or the other receiving transducer. The turning angle of the transmitting transducer unit in a state where the sensor unit coincides with the origin a is defined as a deflection angle θ.

Here, even if the received sound pressure pulsates every moment, the increase / decrease in the sound pressure affects the one receiving transducer section and the other receiving transducer section at the same rate, and is thus obtained. No change occurs in the ratio between the power and the power, and the time when the ratio becomes maximum or minimum can be accurately detected in a stable state.

An ultrasonic flow velocity measuring device according to a fifth aspect of the present invention is a device for measuring the flow velocity in an open channel, wherein an arbitrary virtual measurement line B orthogonal to the open channel intersects with the other end of the open channel. A point is set as an origin a, and a transmitting transducer portion disposed at one end on the virtual measurement straight line B of the open channel and a distance d in a direction orthogonal to the virtual measurement straight line B at the other end. Output signals of a pair of receiving transducer units arranged at intervals and receiving ultrasonic waves from the transmitting transducer unit, and at least one of the pair of receiving transducer units displaced in the orthogonal direction. The center of the directional characteristic of the ultrasonic wave at the position where the magnitudes of the ultrasonic waves are equal is measured as the displacement point b, and the deflection distance l
An arithmetic and control unit that performs any or all of the measurement of the time t until the ultrasonic wave reaches the receiving transducer unit from the transmitting transducer unit, the measurement of the sound speed c of the ultrasonic wave, and the like. It is characterized by having.

The ultrasonic flow velocity measuring device according to a sixth aspect of the present invention is characterized in that, in the fifth aspect, the reception output signal of one of the receiving transducer units is U ₁ , and that of the other receiving transducer unit is U ₁ . The reception output signal is defined as U _2, and U ₂ / U ₁ is the maximum or U
₁ / U ₂ is minimum, the other received trans du - the position of the support portion as a measurement point b, determine the distance between the origin a described above with the measurement point b as a deflection distance l, ultrasound transmitter A flow rate measuring device for an open channel having an arithmetic and control unit for performing any or all of the measurement of the time t from the transducer unit to the receiving transducer unit, the measurement of the sound speed c of the ultrasonic wave, and the like. It is.

The ultrasonic flow velocity measuring device according to claim 7 is a device for measuring the flow velocity in an open channel, wherein an arbitrary virtual measurement line B orthogonal to the open channel intersects with the other end of the open channel. A point is set as the origin a, and the transmitting transducer section is rotatably disposed in one end on the virtual measurement straight line B of the open channel, and is orthogonal to the virtual measurement straight line B in the other end. A pair of receiving transducers arranged at positions where the distances are spaced in the direction and the magnitudes of the respective output signals are equal when the center of the directional characteristic of the ultrasonic wave reaches the origin a; The transmitting transducer section is connected to the receiving transducer section, and the transmitting transducer section is rotated so that each of the pair of receiving transducer sections transmits the signal from the transmitting transducer section. After receiving the ultrasonic waves, the output signals are equal in magnitude. Outgoing transformer du for measuring linear B - measuring the rotational angle of the support portion as a deflection angle theta, the sound velocity c measurement of ultrasound, such as arithmetic and control unit that performs, characterized by having a city.

The ultrasonic flow velocity measuring device according to claim 8 is
8. The transmitting transducer unit according to claim 7, wherein the transmitting transducer unit is rotatably disposed within one end of the open channel on the virtual measurement straight line B;
A pair of receiving transducers arranged in the other end at intervals d in a direction orthogonal to the virtual measurement line B, and with the other receiving transducer being aligned with the origin a; One of the receiving transducers connected to the transmitting transducer section and the receiving transducer section and rotating the transmitting transducer section to receive the ultrasonic waves transmitted by the transmitting transducer section. The reception output signal of the receiving section is U ₁ and the reception output signal of the other receiving transducer section is U _2, and U ₂ / U ₁ is maximum or U ₁ / U ₂ is minimum;
The rotation angle of the transmitting transducer unit with respect to the virtual measurement straight line B is measured as a deflection angle θ, and the sound speed c of the ultrasonic wave is measured.
Calculation / control device for performing the above-mentioned operations.

The ultrasonic flow velocity measuring apparatus according to the ninth aspect of the present invention is the apparatus according to the fifth, sixth, seventh, and eighth aspects, wherein the receiving transducer section disposed in the other end of the open channel is virtually measured. In this configuration, a plurality of transducer pieces are arranged in a direction orthogonal to the straight line B, and each of the transducer pieces is connected to an arithmetic and control device.

Here, the receiving transducer section is composed of a large number of transducer pieces, and any one of the transducer pieces is selected to mechanically move the transducer. As a result, an operation equivalent to displacing at least one of the receiving transducer units is obtained.

The calibration inspection method according to claim 10
Has a transmitter transducer at one end in the tank.
In addition, the transmission of the transmission transducer part
A pair of receiving transformers spaced at a distance d in the direction orthogonal to the
A transducer section is arranged, and a transmitting transducer section and a receiving transducer are arranged.
Along with the transducer at various positions along the direction d
And translate it to a pair of receiving
Each of the transducer units receives a call from the outgoing transducer unit.
And the respective output signals are U_{twenty one}= U _{twenty two}Etc.
Or output signal U_{twenty one}And U_{twenty two}Input to the differential amplifier.
And the output signal of the differential amplifier becomes ΔU = 0, or
Each output signal U₁ And U_Two Is the largest or smallest ratio,
Detect the position of the pair of receiving transducers, and
To compare with the corresponding outgoing transducer travel.
Features.

The tenth aspect of the present invention is to easily inspect and adjust (calibrate) the characteristics and accuracy of the method and apparatus according to the present invention. If you move at the same speed for a predetermined time,
This is established because the moving distance is equal to the ultrasonic deflection distance.

[0052]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the principle of the present invention will be described with reference to FIG. 1. An arbitrary virtual measurement line B substantially orthogonal to an open channel, and one side end on the virtual measurement line B of the open channel. When the transmitting transducer unit 1 is arranged and the receiving transducer unit 2 is arranged in the other end, FIG. 1 shows that the ultrasonic wave starting from the fixed point 0 to the fixed point a is transmitted through the water. The phenomenon of propagation and reaching the fixed point a or b is exaggeratedly described.

When the water is stationary, that is, when the flow velocity is V = 0, the ultrasonic wave propagating from the point 0 reaches the point a, but when the water flows at the flow velocity V, the ultrasonic wave reaches the point. Becomes b. At this time, the distance 1 (small L) between the point a and the point b is as shown in Expression (1). Here, B is the distance between point 0 and point a, c is the speed of sound in the fluid, and t is the time required for the ultrasonic wave to propagate. Also, the angle θ formed by the 0a line and the 0b line
Is as shown in Expression (2).

[0054]

(Equation 5)

In Equation (1), l (small L) is the deflection distance of the ultrasonic wave, θ in Equation (2) is the deflection angle of the ultrasonic wave, and from both equations, the flow velocity V is expressed as in Equations (3) and (4). The deflection distance l
And the sound velocity c or the propagation time t, or the deflection angle θ and the sound velocity c, to obtain the flow velocity V.

Note that the deflection angle θ here is a geometric angle in the drawing, and the ultrasonic wave does not propagate while changing its propagation direction to the angle θ. The direction in which propagation began is unchanged, but only the apparent geometric angle θ results from the movement of the propagation medium. A plurality of arrows on the curve 0b line in FIG. 1 indicate this phenomenon that the direction in which propagation starts is unchanged.

If the horizontal average flow velocity V is obtained by measuring the deflection distance 1 and the sound velocity c or the propagation time t or the deflection angle θ and the sound velocity c according to the equations (3) and (4), the conventional technique is used. The above-mentioned three problems that occur when measuring are solved at once. The reason is that, in a practical flow velocity region, since the ultrasonic wave propagates on a line substantially equal to the flow measurement cross section S, the cross-sectional area S corresponding to the average flow velocity to be measured can be specified. However, since a continuous sine wave can be used instead of a pulse, attenuation due to propagation is reduced.

Even if the degree of attenuation changes from time to time and the received signal level pulsates, the check level is not used. Therefore, it is enough to amplify the received signal appropriately, and it is erroneously taken in. You can't miss it.

Furthermore, no matter how large the angle α of the oblique flow component flow velocity, the flow velocity directly measured is always only the component perpendicular to the cross section S. If the direction of the flow velocity coincides with the ultrasonic wave propagation direction, l (small L) = 0, θ
= 0, and at an angle of 90 ± α with respect to the ultrasonic wave propagation direction, l (small L) and θ are as shown in Expression (5). Here, Vcos α = _V⊥, that is, only the flow velocity component to be measured perpendicular to the cross-sectional area S is appropriately measured.

Next, FIG. 2 is a graph showing the relationship between the deflection distance l in the present invention.
This shows the outline of the measurement method and equipment, and is almost perpendicular to the open channel
Open channel of any virtual measurement straight line B (flow measurement cross section S)
The point of intersection with the other end is set as the origin a, and the temporary
The transmitting transducer part 1 is located at one end on the imaginary measuring line B.
And the above-mentioned virtual measurement line B in the other end.
At a predetermined interval d in the direction orthogonal to
Sducer part 2₁ , 2 _Two Outgoing transducer
An ultrasonic oscillator 3 is connected to the unit 1, and a pair is provided as necessary.
Receiving transducer section 2₁ , 2_Two Each is differential amplification
Connected to the vessel 4. In the illustrated embodiment, the receiving transformer
Ducer part 2₁ On the upstream side, the receiving transducer unit 2
_Two Is located downstream.

The transmitting transducer unit 1 transmits an ultrasonic wave from one end on the virtual measurement straight line B of the open channel toward the center a of the directional characteristic toward the origin a of the other end. The directivity is bilaterally symmetric, and the ultrasonic waves are transmitted with a sharp directivity having a small directivity angle. The same applies to the following description.

[0062] FIG. 2 (a), for example, the standby secondary includes a measurement start, a pair of receiving transformer du - in the case of arranging the center of the support portion 2 _1, 2 ₂ to match the origin a, reception trans du - Sa 2 ₁ and the origin a, reception trans du - the support part 2 ₂ and the origin a, are equidistant in each d / 2 intervals.

When the flow velocity is V = 0 as shown in FIG.
Since the center of the directivity of the ultrasonic wave reaches the origin a, a pair of receiving transformer du - Sa 2 ₁ and 2 the magnitude of the _second respective output signals U ₂₁ and U ₂₂ become identical to each other (U ₂₁ =
U ₂₂ ), when this output is input to the differential amplifier 4, the output becomes ΔU = K (U ₂₂ −U ₂₁ ) = 0. Here, K is the amplification degree of the differential amplifier 4.

On the other hand, when the flow velocity is V ≠ 0, the ultrasonic wave from one end deflects by the deflection distance 1 obtained by the equation (1) and reaches the other end, so that the receiving transformer on the upstream side du - output signal Sa 2 ₁ receiving transformer du downstream - smaller than the output signal of the sub unit _{2 2, ΔU = K (U} 22
−U ₂₁ )> 0.

[0065] Therefore, as shown in FIG. 2 (b), the reception trans du - when is simultaneously displaced in a downstream direction (i.e. the direction d) perpendicular to Sa 2 ₁ and 2 ₂ in the virtual measuring linear B, the ΔU with it decreased Then, ΔU = 0, and when the displacement is further continued, the sign of ΔU is reversed and increases as a negative value (ΔU <
0).

[0066] The .DELTA.U = became point A to 0, the reception trans du - it means that service unit 2 ₁ and 2 ₂ are the magnitude of the output signal by receiving ultrasonic waves are equal, thus originating trans du - the sound pressure peak arrival position of the transmitting ultrasound from Sa unit 1, since the directivity in this embodiment is symmetrical, both received trans du - Sa 2 _1, 2 ₂ d / 2 points are intermediate points This point becomes the measurement point b, and the distance between the measurement point b and the origin a is the ultrasonic deflection distance 1 to be measured.

On the other hand, a pair of receiving transducer sections 2 ₁
When only one of ₂ and 2 is displaced, for example, FIG.
In (b), the reception trans du - a support portion 2 ₁ keep always fixed at the position in the figure, the reception trans du - Sa 2 ₂
Only be _{displaced, U 21 = U 22 (ΔU} = 0) d of when it becomes '/ 2 (d' is received trans du - increases or decreases along with displacement of the support part 2 ₂₎ points the same sound pressure This is the peak arrival point, and FIG. 2 (b) shows this point. Therefore, the distance between this d '/ 2 point and the origin a is obtained as the deflection distance l.

[0068] Then if when the flow velocity V is a little greater than in the case of FIG. 2 (b), receives trans du - Sa 2 ₁
Output signal U ₂₁ of less reception trans Du than in FIG - the output signal U ₂₂ of the support unit 2 ₂ is large, the reception trans du - as to displace the support part 2 ₂ Output signal U ₂₂ is decreasing On the other hand, the fixed reception trans du - the output signal U ₂₁ of the support unit 2 ₁ is immutable, at some point U ₂₁ = U ₂₂ (ΔU
= 0) becomes the reception trans du - displacement point of the support part 2 ₂ occurs. The arrival point of the sound pressure peak is the middle point of d 'at this time (that is, 1/2 point), and the distance between this point and the origin a is the deflection distance l.

[0069] In the above description, the receiving transformer du located upstream - but on illustrated support portion 2 ₁ was used an example of fixing the origin a, receiving the downstream by the terms of the measurement range and field trans du - to support unit 2, the mobile receives trans du - - or fixing the support part 2 _2, or a fixed reception trans du support section 2 the fixed received trans du - beyond the support section 2 , From the upstream side to the downstream side or from the downstream side to the upstream side.

[0070] In processing, in the embodiments described above, the reception trans du - Comparing the means for displacing only either one means for displacing both support portions 2 ₁ and 2 _2, the latter is for the displacement The moving device can be reduced in size and weight.

The fixed-side receiving transducer unit 2
If the disposition position is appropriately selected, the displacement amount of the receiving transducer unit 2 on the moving side is increased as compared with the former means, so that the resolution in measuring the displacement amount is increased and the accuracy is improved. . In particular, as shown in FIG. 2B, if the fixed-side receiving transducer section 2 is arranged at the origin a, the above-mentioned distance d '/ 2 is equal to the deflection distance 1 as it is, that is, d' = 2.
1 (2 small el). Therefore, when the river width is relatively small, the deflection distance l is also small, and the latter is the optimal means.

On the other hand, the former means uses the river width and the flow velocity V
Is large, and the change range (measurement range) of the flow velocity V is large. Further, the former means selects an interval d at which the sound pressure change gradient with respect to the displacement amount can be remarkably increased in accordance with the directional characteristics of the transmitting transducer unit 1, as described later, and sets the interval d to Since it can be used regularly, the accuracy of checking the time point U ₂₁ = U ₂₂ (ΔU = 0) can always be increased.

At this point, a pair of receiving transducers is provided at the other end.
Instead of the above-described configuration in which the transmitter 2 is disposed, a means for directly searching for the sound pressure peak by disposing only one receiving transducer 2 may be considered. That is, while the receiving transducer unit 2 is displaced in a direction orthogonal to the virtual measurement line B, the ultrasonic wave transmitted from the transmitting transducer unit 1 is received, and the output signal U is maximized. The displacement position of the receiving transducer unit 2 is set as a measurement point b.

However, since the sound pressure peak of the ultrasonic wave does not appear so clearly, this displacing receiving transducer is displaced.
There is a large error in specifying the maximum sound pressure receiving position using only the sub-unit 2 alone and with the maximum value of the single received output signal.

If the output signal U is greatly amplified for this purpose, noise is also amplified this time, which also causes an error in the detection of the true sound pressure (signal) peak point. Further, since the reception intensity of the ultrasonic wave fluctuates and pulsates instantaneously, the sound pressure at the sound pressure peak point naturally also pulsates, and the reception output signal at the peak point becomes smaller than that at the other points. Instantaneous occurrences often occur, and not only a supplementary error occurs in detecting the maximum sound pressure arrival point, but also measurement often becomes impossible. this is,
The same applies to the case where the receiving transducer unit 2 described later is fixedly arranged and the deflection angle θ is obtained.

[0076] Therefore, in the above invention two receiving transformer du - with support portion 2, the reception trans du - receiving service unit 2 ₁ and 2 _2, the magnitude of the ultrasonic output signal are equal respectively, or The point (point) at which the ratio between the output signals U ₁ and U ₂ reaches the maximum or minimum value is determined.

As a result, as can be seen from FIG. 3 (a), the signal can be received not in the vicinity of the sound pressure peak where the gradient of the sound pressure change with respect to the displacement amount but in the portion where the gradient of the sound pressure change is large. It becomes unnecessary, and it is possible to accurately grasp the time point (point) to be obtained without being affected by amplification noise.

Even if the received sound pressure pulsates every moment, the increase and decrease of the sound pressure have almost the same amount on both the receiving transducer units 2, so that the comparison of the magnitude of the received output signal is hardly affected. In particular, at the time point (point) of U ₂₁ = U ₂₂ (ΔU = 0), the same amount acts and is completely cancelled, so that no effect occurs. This is the same even when the deflection angle θ is obtained.

Here, the output signal ΔU (= U ₂₁ −) is output through the differential amplifier 4 rather than simply comparing the magnitudes of the two finite output signals and simply finding the point in time at which they become equal.
U ₂₂ ) It is more reliable, easier and more accurate to check whether only one is 0 or not, and more comprehensive improvement in accuracy can be realized. Furthermore, it is widely known that the most accurate way to check that a changing signal has reached a certain value is at the moment when the signal goes to zero.

FIG. 3B shows the receiving transducer unit 2
This shows how the output signal ΔU of the differential amplifier 4 changes with the degree of amplification K with respect to the displacement. It is very easy to increase the amplification K of the differential amplifier 4, and the larger the amplification K, the larger the output signal gradient becomes, which is coupled with the increase in the sound pressure change gradient caused by the value of the distance d. This makes it easier to precisely check whether ΔU = 0.

If the post-processing is performed electrically by using the differential amplifier 4, the output signals U ₂₁ and U ₂₂ which are generated in the ultrasonic wave or in the electric circuit, even if the amplification is large, are performed. Is not only completely removed, including the above-mentioned received sound pressure pulsation, but since ΔU is output as a DC signal, a rectifying circuit or the like is not required.

For example, when the output of the differential amplifier 4 is input to a comparator, and a monostable pulse oscillator (mono stable multivibrator) is activated at the moment of ΔU = 0, a pulse is transmitted. received by the pulse transformer du - it can know the size of the support portion 2 ₁ and 2 ₂ of the output signal becomes equal. Of course, the same effect can be obtained when the deflection angle θ is obtained.

[0083] The gradient of change of the sound pressure itself so large ideal pair of reception trans du - spacing d of Sa 2 ₁ and 2 ₂ is selected from formula d ≧ 2B · tan β. Here, FIG. 3 is a directional characteristic diagram of the transmitting transducer unit 1.
As shown in FIG. 4A and FIG. 4, the maximum sound pressure of the directional characteristic of the transmitting transducer unit 1 is P _max , the sound pressure of the ultrasonic wave which the receiving transducer 2 intends to receive is P ₁ , The angle formed by the line connecting the origin of the directivity and the points P _max and P ₁ is β
And

For example, if the angle at which P ₁ = 0.95 P _max is β =
If 0.05 °, d / B = 2 · tan 0.05 ° = 0.
001745. Therefore, if the virtual measurement line B is 100 m
(Meter), 500m, 1000m, the distance d is
0.175m (meter), 0.873m, 1.75m.

Even if P ₁ / P _max becomes slightly smaller, a larger distance d is obtained while referring to the directional characteristics as described above.
Is determined, the above-described gradient of the change in sound pressure becomes large, and the detection of the time point and the point can be performed with high sensitivity. Conversely, when the distance d is reduced to save space and reduce the size and weight of the apparatus, it is only necessary to reduce the directional angle of the transmitting transducer 1 (it is not difficult to make the directional angle 2-3 °). Or P ₁ /
Although P _max may be selected to be relatively large, in this case, it is necessary to increase the sensitivity and the degree of amplification of the differential amplifier 4 in order to complement electrically. This is the same even when the deflection angle θ is obtained.

As means for obtaining the measurement point b,
Shin transducer unit 2₁ And 2_Two Of each output signal
It is also conceivable to measure when the rate is highest.
That is, for example, in FIG.
2₁ And the ultrasonic reception output signal
₁ , The other receiving transducer section is 2_Two As its receiving
Output signal to U_Two While receiving the interval d ''
Transducer part 2₁ And 2 _Two Or in FIG. 2 (d)
Receiving transducer part 2_Two Only the solid line from the chain line
Displaced as shown in_Two / U₁ Is the maximum value.
Or U₁ / U_Two Detects the point where is the minimum value.

U ₂ / U ₁ becomes the maximum value, or U ₁ / U ₁
The point where U ₂ is the minimum value, originating trans du - a position for receiving the sound pressure peaks of the outgoing ultrasound from sub unit 1, therefore displaced the other received trans du - Sa 2
The position of ₂ can be determined as the measurement point b. still,
U ₂ / U _{1 and the} like can be easily obtained by inputting U ₂ and U ₁ to the division circuit 4 ′, and a rectification method performed as necessary is well known.

Of course, any of the receiving transducer units is
₁ and an arbitrary or assigned as 2 _2, and conversely at the assignment of the above embodiments, at least receive trans du - to displace the support part 2 _1, U ₁ / U ₂ is the maximum value, or U ₂ / receiving transformer du at which U ₁ is the minimum value -
Position of the service unit 2 ₁ is the sound pressure peak arrival point, it is also possible to measure the point b to be determined. In the case where only one receiving transducer unit 2 is displaced,
It may be displaced on both sides of the other fixed-side receiving transducer unit 2.

The means by which one of the two receiving transducer units 2 directly detects the peak point of the sound pressure as described above is as described above. to change gradient is small, the other of the receiving transformer du detecting here - output signal change gradient of the sub unit 2 ₂ in terms of fewer, one of the receiving transformer du described earlier - the peak point only support part 2 This is similar to the case of directly detecting.

However, the two receiving transducers
The means for detecting the peak point of the sound pressure by one of the sub-units 2 can realize highly accurate detection. This is because, unlike the case where detection is performed by only one receiving transducer unit 2,
The other received trans du - not only the support portion 2 _2, one of the receive transformer du - because received any support unit 2 _1, to detect the maximum or minimum by taking the ratio of the two output signals.

That is, the other receiving transducer section 2 ₂
Even if the output signal changes less slope, one of the receive transformer du - the output signal change gradient of the sub unit 2 ₁ can be increased, variation gradient of both ratios is become larger. Further, even if the received sound pressure pulsates every moment, the increase / decrease of the sound pressure affects the one receiving transducer part and the other receiving transducer part at the same rate, so that the ratio of the two to be determined is required. Does not cause any change as described above.

[0092] In addition, the reception transformer du - support unit 2 ₁ and 2 ₂
The distance d '' when left to simultaneously displace maintaining the, and FIG. 2 (c) and 4 as apparent from d '' = d / 2, so, from d '' ≧ B · tan θ , U 2 An interval d ″ at which a large change gradient of / U ₁ is obtained can be obtained.

As described above, the principle of the means for detecting the center of the directional characteristic from the ratio of the output signals U ₁ and U ₂ can be applied to the case where the deflection angle θ is obtained. In this case, however, the pair of receiving transducer units 2 may be fixedly arranged, and one of them is located at the origin a.

[0094] embodiment of FIG. 2 described above, per seek deflection distance l, the reception trans du - Sa 2 ₁ and 2 ₂ or at least one receiving transformer Du of the pair, - a support unit 2, the virtual measurement By mechanically displacing in the direction perpendicular to the straight line B, the sound pressure peak of the ultrasonic wave transmitted from the transmitting transducer unit 1 is determined because the received output signal becomes equal or the ratio becomes maximum / minimum. , Measurement point b.

On the other hand, in the embodiment shown in FIG. 5, the transmitting and receiving transducer units 1 and 2 are not rotated or displaced as described above. trans du - Sa 2 ₁ causes the example origin a position, reception trans du - Sa 2 _2, in a direction perpendicular to the virtual measuring linear B, l (small El) _{ma x}
From l (Small El) number of n transformer Du which enumerated the entire section of the _min - Sa piece 2i fixedly arranged integrally configure the reception trans du - Sa 2 ₁ and the transformers du - Sa piece 2i are connected to a dividing circuit 4 '.

In this case, there is a method of using n division circuits 4 '. However, each output of each transducer piece 2i is connected to a switch (sw), and is sequentially switched one by one to form one division. It may be connected to the arithmetic circuit 4 'to calculate U _i / U ₁ . In this case, the other input terminal of the divider circuit 4 'receives trans du - Sa 2 ₁ is connected.

Then, the ultrasonic wave transmitted toward the origin a
However, there is a peak of the sound pressure depending on the flow velocity.
2i, and its output signal ratio U_i / U₁ Is the largest
, The transducer piece 2i is
Receiving transducer unit 2 _Two That is. Immediately
That is, selecting one of the many transducer pieces 2i
Receiving transducer unit 2_Two And the result
Receiving transducer section 2_Two Is the same as
And

For example, if a section from l (small L) _max to l (small L) _min is divided into 100 and a mosaic is made up of 100 transducer pieces 2i, V _max
The V _min will be measured with a resolution of 1/100. _{If, ΔV = V max -V mi n} = 3m / s-0.5m
If / s, 2.5 / 100 = 0.025m / s resolution flow rate can be measured at the measurement error in this case becomes the worst condition V _min is, [delta] _{V min} = 0.025 × 10
0 / 0.5 = 5%.

[0099] Of course, the output signals U ₁ = U _i or reception trans Du, - service unit 2 ₁ and the receiving transformer du - Sa 2 _i
Is input to the operational amplifier 4 and d / 2 at the time when .DELTA.U = 0 is recognized as the measuring point b. In this case, the receiving transducer unit 2 is selected according to the distance d and the measuring range. The arrangement position of ₂ is different from the above, and the resolution becomes 1/200 and δ _{V min} also becomes 0.25% because of d / 2.

Further, when the measurement range is from a flow velocity of 0, etc.,
Receiving trans du - without using the support unit 2 ₁ trans du most upstream - at the same time placing the support piece 2i origin a, the output, the receiving transformer du described above - be used instead of the output of the sub unit 2 ₁ Is also possible.

Then, at a distance d or d ″,
A transducer piece 2i and a transducer piece 2 _{i + d} ,
Alternatively, the transducer piece 2i and the transducer piece 2
_{i + d ″} , and U ₁ = U ₂ (ΔU =
0) or U ₂ / U ₁ is also possible to obtain a measurement point b after the timing when the maximum or minimum. The reception trans Du - reception trans Du corresponding to the sub unit 2 ₁ - position of the support portion 2 is not limited to the origin a in any case.

In the present invention and its embodiments in the above-mentioned claims, the receiving transducer unit 2 comprises:
It is not limited to a pair. A plurality of pairs or a plurality (particularly an odd number) may be used depending on the flow rate measurement range or the situation at the measurement site.

[0103] For example, FIG. 6 (a), a pair of receiving transformer Du with a spacing d ₁ and d ₂ - with support portions 2 ₁ and 2 ₂ integrally, each suitable reception trans du - Sa 2 pairs U
₂₁ = U ₂₂ (ΔU = 0), or as shown in FIG. 6 (b), one of a plurality of receiving transducer units 2 is appropriately arranged to provide optimum U ₂ / U ₂₁ or U _2. / _{22 or} the like, the sound pressure peak point (or the measurement point b) is detected. Further, as shown in FIG. 6 (c), for example, using three reception transducer units 2, U ₂₁ = U ₂₂ (ΔU = 0) and U ₂
/ A U ₂₁ and U _2/22 or the like can also be detected measurement point b by utilizing in combination.

Next, FIG. 7 schematically shows a method and an apparatus for measuring the deflection angle θ in the present invention, in which the open channel of an arbitrary virtual measurement straight line B (flow measurement cross section S) substantially orthogonal to the open channel. The point of intersection with the other side end is set as the origin a, and the transmitting transducer unit 1 is located within one side end on the virtual measurement straight line B of the open channel.
The rotatably with placing a pair of receiving transformer Du spaced a predetermined distance d in a direction perpendicular to the virtual measuring line B described above in the other end - the support unit _{2 1, 2 2, d /} 2 points Are fixedly arranged so as to coincide with the origin a.

When the flow velocity is V = 0, the transmission transducer
The ultrasonic wave transmitted by the sub-unit 1 toward the origin a propagates along the virtual measurement straight line B, but when the flow velocity is V ≠ 0, the ultrasonic wave is deflected and reaches the point b ′ on the other end. Therefore, the transmitting transducer unit 1 is rotated in the upstream direction so that the sound pressure peak of the ultrasonic wave reaches the origin a. When the ultrasonic wave reaches the origin a, the rotation direction is changed to the origin a. Is the deflection angle θ.

Unlike the above-described apparatus and method for performing parallel movement, here, since only the transmitting transducer unit 1 has a simple rotational movement, the driving device is mainly simplified, and the flow velocity at various water depths is measured. It is possible to arrange all the transmitting transducer units 1 on one rotating column.

Means for obtaining the time when the rotation angle becomes the deflection angle θ from the output signal U ₂₁ = U ₁₂ or from the output signal ΔU = 0 of the differential amplifier 4, and the output signals U ₁ and U
Means for obtaining from the ratio of ₂ are transducer pieces 2i
This is the same as the above-described case of measuring the deflection distance 1 including an example of using. However, when determining the ratio, the reception trans du - placing either support portions 2 ₁ and 2 ₂ in origin a. Further, the rotation of the transmitting transducer unit 1 requires precise control such as step rotation at a minute angle.

Now, the ultrasonic deflection distance l or the deflection angle θ
In order to calculate the velocity V by the equation (3) or the equation (4), the time t during which the ultrasonic wave propagates through the virtual measurement straight line B section or the sound velocity c in water must be measured. However, since the method of measuring the propagation time t or the sound speed c is widely known, an appropriate method may be selected (for example, the sound speed c).
Japanese Patent Application Laid-Open No. 9-189590 and Japanese Patent Application No. Hei.
Invention of No. 0-279306).

[0109]

FIG. 8 shows a specific embodiment of the receiving transducer section 2 of the apparatus for determining the deflection distance 1 according to the present invention. , A plurality of rack rods 6 are mounted at predetermined intervals in the up-down direction and in a posture that is horizontal and orthogonal to the virtual measurement straight line B, respectively.

[0110] rack rod 6 is horizontally moved to the left or right depending on the direction of rotation of the pinion 7 in Kan桿5, a pair of receiving transformer du - Sa 2 ₁ and 2 _2, rack at predetermined intervals d rod The shaft 8 of the pinion 7 fixed to 6 and inserted into the tube rod 5 is connected to a speed reducer 10 for reducing the rotation speed of the motor 9.

The motor 9 is connected to a rotation speed measuring device 11 of the motor 9, and also connected to a timer 12 and a power switch 13 operated by a signal from the timer 12.

On the other hand, a pair of receiving transducer sections 2 ₁
And 2 ₂ are connected to the comparator 14. The comparator 14 generates an output signal when the magnitude of the output signal of the differential amplifier 4 becomes ΔU = 0, and operates the monostable pulse oscillator 15 connected to the comparator 14.

The monostable pulse oscillator 15 and the rotation speed measuring device 11 are connected to a digital converter 16. The digital converter 16 converts the number of rotations of the motor 9 into the moving distance of the rack 6, and when the pulse of the monostable pulse oscillator 15 is input, the value of the deflection distance 1 measured at that moment. As a code signal to the memory circuit of the flow velocity calculating device 17. Flow velocity calculator 17
Calculates the equation (3) of the flow velocity V and transmits the code signal of the V value to the flow rate calculation device 18.

The measured value of the sound velocity c (code signal) is input to the flow velocity calculating device 17 when the flow velocity measurement is started (the sound velocity measuring device, the time measuring device, and the rack rod 6 are connected). A control device and the like that wait at the reference point are not shown).

In the memory circuit of the flow velocity calculating device 17, virtual measurement straight lines B at various water depths are used for the flow velocity V calculation (however, it is unnecessary in the case of time measurement). Various data used for the flow rate Q calculation including the width (width) of the river are input and recorded.
Since the pinion 7 and the rack rod 6 operate in water, they may be made of a synthetic resin material such as polyurethane.

Next, FIG. 9A is a vertical cross section parallel to the virtual measurement line B, and FIG. 9B is a plan view of the portion, and a plurality of transmitting transducers are arranged above and below. An ultrasonic sine wave oscillator 3 for exciting the transmitting transducer unit 1 is connected to the transmitting unit 1, and the ultrasonic wave is transmitted from all the transmitting transducer units 1 at the same time. Yes in the different frequencies the emitted frequencies from each other, the reception trans du - resonance frequency of the service unit 2 ₁ and 2 ₂ are also respectively corresponding outgoing trans du - are to match the frequency of the service unit 1.

Incidentally, a timer 19 and a power switch 20 operated by the timer 19 are connected to the ultrasonic sine wave oscillator 3. The timer 19 is synchronized with the above-described timer 12 on the receiving side, and the power switches 13 and 20 are turned on based on the designated flow rate measurement cycle to operate the apparatus.

In the operation of the above-described apparatus, first, when the flow rate measurement time comes, the timer 12 on the receiving side and the transmitter 19 operate the power switches 13 and 20, respectively, to start the measurement.
Then, the transmitting transducer unit 1 continuously transmits ultrasonic waves, the motor 9 starts rotating, and the rotation speed measuring device 11 continuously measures the rotation speed of the motor 9, and outputs an output signal. Is input to the converter 16.

[0119] mode - because the motor -9 rotates the pinion 7 is rotated, the rack rod 6 moves horizontally, thus receiving trans du - Sa 2 ₁ and 2 _2, from the defined position in the virtual measuring line B Start moving in a direction perpendicular to the direction. And while moving the received trans Du - instant the magnitude of the difference 2 ₁ and 2 ₂ of the output signal becomes the same, the output of the differential amplifier 4 becomes .DELTA.U = 0, converter monostable pulse is generated 16 since the input to, measured at this moment reception trans du - distance from the origin a Sa 2 ₁ and 2 _2, that is, to enter the ultrasonic deflection distance l in a flow rate calculation unit 17.

Generally, the flow velocity in the surface layer is high and the flow velocity in the vicinity of the riverbed is low.
The order of ΔU = 0 starts from the receiving transducer section 2 near the riverbed and ends at the receiving transducer section 2 near the water surface. Incidentally, the receiving transducer unit 2 may be moved from the downstream side toward the origin a.

The time required for measuring the flow rate is determined by the moving speed of the rack rod 6 and the width of the river. By appropriately selecting the deceleration coefficient of the speed reducer 10, the moving distance of the rack rod 6 per rotation of the pinion 7, the resolution of the rotation speed measuring device of the motor 9, etc., the ultrasonic deflection distance l can be measured with high accuracy. .

As described above, FIGS. 8 and 9 show an embodiment of the apparatus for obtaining the deflection distance 1 according to the present invention, but the apparatus for obtaining the deflection angle θ may have substantially the same configuration. However, a rod on which a plurality of transmitting transducer parts 1 are mounted at predetermined intervals in the vertical direction is required to be able to rotate the shaft with high precision, and a drive source, a drive control device, a rotation angle measuring device, and the like are required.
Also, since the receiving transducer unit 2 is fixedly arranged,
There is no need for a device for horizontal movement or a device for measuring the amount of displacement (both not shown).

Further, in all the above-mentioned flow measuring methods and apparatuses, there is no limitation that the transmitting transducer unit 1 and the pair of receiving transducer units 2 have to be paired. In some cases, the flow rate calculation accuracy may be slightly degraded, but for example, a plurality of pairs of receiving transducer units 2 are used for one transmitting transducer unit 1 along the depth direction. Sometimes.

The method and apparatus for measuring the flow velocity of an open channel according to the present invention operate in the above-described configuration. In general, in the case of a measuring apparatus, the characteristics and accuracy of the apparatus are inspected or adjusted (calibrated). One embodiment of an apparatus and method for calibrating or testing this characteristic is shown in FIG.

FIG. 10 (a) is a plan view of the calibration inspection apparatus, and FIG. 10 (b) is a sectional view thereof.
The transmitting transducer ₁ is immersed on one side of the device, and the receiving transducer ₂ composed of the receiving transducers 21 and 22 spaced at the other side is immersed on the other side. Lead screw 22 connected to micrometer 23
So that they can move in parallel in the d direction along the side ends in the water tank 21.

[0126] According to this configuration, first outgoing trans Du - reception trans du with arranging the support portion 1 to the reference point b _'0 - transmits ultrasonic waves toward the support unit 2, micrometers 2
3 to move the receiving transducer unit 2 left and right (d direction, up and down in the figure) while ΔU = 0 (U ₂₁ = U
₂₂ ) Find the position that will be.

Suppose the directional characteristics of the transmitting transducer unit 1
Is completely symmetric, the receiving transducer
Sub part 2₁ And 2_Two The center point d / 2 of the
Reference point b 'of sub part 1₀Matches the exact position of. Asymmetric field
In this case, the center point d / 2 does not coincide with the directly opposite position,
It doesn't matter. ΔU = 0 (U_{twenty one}= U_{twenty two}B) ₀ 
Should be recorded and displayed.

[0128] Next, by operating the micrometer 23, originating trans du - after moving fixing the support part 1 l (the small El) 'is _only displaced b' ₁ position, again received trans du - Sa 2 By moving ₁ and 2 ₂ , ΔU = 0 (U ₂₁ =
The displacement amount l (small el) ₁ of the position b _{1 at} the moment when the moment reaches U ₂₂ ) is measured by the micrometer 23, and the difference of the displacement amount l (small el) ₁ is compared with the above l (small el) ′ _1. To inspect.

[0129] In this way, the outgoing trans du - a support portion _{1 b '1, b' 2} , b '3, b' 4 on the mobile and fixed to the position of ......... b _'max, reception trans du - Move the unit 2 to ΔU
= 0 (U ₂₁ = U ₂₂ ) Displacement l of the position b _{n at} the moment
(Small L) _n is measured, and these are compared with the displacement l (Small L) ' _n of the transmitting transducer unit 1, _respectively , to inspect the measurement error in the entire l (Small L). The electronic circuit can be adjusted to calibrate to the required characteristics. About 5 m is sufficient for the length of the water tank 21.

[0130] In the calibration test, knowing measurement error [delta] _l of l (small El), the actual total flow rate measurement error [delta] _V is as equation (6). Here, δ _c and δ _B are the measurement error of the sound velocity c and the measurement error of the distance from the transmitting transducer unit 1 to the origin a.

[0131]

(Equation 6)

The reason why the calibration test can be easily carried out in this way is that the transmitting transducer unit 1 is supposed to transmit from the transmitting transducer unit 1 at the same speed V as the horizontal average flow velocity at the measurement site. receiving trans du - if moved by the ultrasonic wave propagation time until the support part ₂ 2 t = B / c the same time, Vt = l (Small El) of equation (1), which is an ultrasonic deflection distance This is because they are the same.

[0133] Incidentally, the calibration inspection method, apparatus using an output signal U ₂₁ = U ₂₂ without using the differential amplifier 4, or the reception trans du - Sa 2 ₁ or 2 ₂ or a displaces output The present invention can be applied to a device for obtaining a signal (U ₂₁ = U ₂₂ (ΔU = 0)), and further to a device utilizing a point in time when the ratio between the output signals U ₁ and U ₂ becomes maximum or minimum.

Further, the transmitting transducer unit 1 and the receiving transducer unit 2 are moved in parallel, and the respective displacements l
Instead of measuring and comparing the (small L) ' _n and the displacement l (small L) _n , both are rotated coaxially,
Likewise By measuring and comparing the rotational angle theta _n and theta _'n, there is a method of calibrating and testing in the water tank 21.

[0135]

According to the method and the apparatus for measuring the flow velocity of an open channel according to the present invention, the flow velocity of a fluid can be measured accurately and easily by utilizing the deflection phenomenon of ultrasonic waves in the fluid. Thus, according to the calibration inspection method of the present invention, many excellent operational effects can be obtained, such as that the calibration inspection of this device can be easily and accurately achieved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a deflection phenomenon of an ultrasonic wave which is a principle of the present invention.

FIG. 2 schematically shows a method and an apparatus for measuring a deflection distance 1 according to the present invention, and is an explanatory view at various positions of a receiving transducer unit 2.

3A is an explanatory diagram showing a sound pressure change gradient of an ultrasonic wave, and FIG. 3B is a diagram illustrating an output signal ΔU of a differential amplifier with respect to a displacement of a receiving transducer section, which varies with an amplification degree K. It is explanatory drawing which showed the situation.

FIG. 4 is a diagram illustrating the principle of selecting an interval between receiving transducers.

FIG. 5 is an explanatory diagram showing one embodiment of a receiving transducer unit.

FIG. 6 is an explanatory diagram showing an embodiment in which one or more pairs of receiving transducer units are used.

FIG. 7 is an explanatory view schematically showing a method and an apparatus for measuring a deflection angle θ in the present invention.

FIG. 8 is an explanatory diagram showing another embodiment of the receiving transducer unit.

FIG. 9 is an embodiment showing the entire apparatus of the present invention,
(A) is an explanatory view showing a vertical section parallel to the virtual measurement line B, and (b) is a plane view of the portion.

FIG. 10 is a diagram illustrating a calibration / inspection apparatus and an embodiment of the present invention;
(A) is a plan view, and (b) is a cross-sectional view.

11 (a) is a cross-sectional view of the prior art,
(B) is a river plan view.

FIG. 12 is a change diagram of a cross section of flowing water in a river.

FIG. 13 is an explanatory diagram showing a measurement error of a mixed flow velocity in the related art.

FIG. 14 is an explanatory diagram showing a form of an ultrasonic pulse and its change.

[Explanation of symbols]

1; transmitting transducer section; 2; receiving transducer
Subunit, 3; oscillator, 4; differential amplifier, 5; tube rod, 6: rack rod, l (small el); deflection distance, θ: deflection angle.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Haksaw, Chang Pang-Dang, Yatap-dong, Changmima, Gyeonggi-do, Songnan, Korea 102-1301 (72) Inventor, Yasuo Ito 1-4-7, Miyamae, Suginami-ku, Tokyo F term (reference) 2F035 AA03 DA07 DA23

Claims (10)

[Claims] 1. A method for measuring the flow velocity of an open channel, comprising:
An intersection point of an arbitrary virtual measurement straight line B substantially orthogonal to the open channel with the other end of the open channel is set as the origin a, and the transmitting transducer unit is disposed within one end on the virtual measurement straight line B of the open channel. A pair of receiving transducer units are arranged in the other end and spaced apart in a direction perpendicular to the virtual measurement line B by at least one of the reception transducer units. B, and each of the pair of receiving transducer units receives an ultrasonic wave transmitted from the transmitting transducer unit with its directional characteristic centered toward the origin a, and receives the ultrasonic wave. The center of the directional characteristic of the ultrasonic wave at the position where the magnitude of the output signal is equal is determined as the measurement point b, and the deflection distance 1 (small el) is determined from the distance between the measurement point b and the origin a. , The deflection distance l and the ultrasonic wave are transmitted by the transmission transformer. Calculating the flow velocity in the open channel from the time t until the laser reaches the receiving transducer section or the value of the deflection distance l, the sound velocity c of the ultrasonic wave, and the virtual measurement linear distance B. Characteristic method of measuring flow velocity in open channels. 2. A method for measuring the flow velocity of an open channel, comprising:
An intersection point of an arbitrary virtual measurement straight line B substantially orthogonal to the open channel with the other end of the open channel is set as the origin a, and the transmitting transducer unit is disposed within one end on the virtual measurement straight line B of the open channel. A pair of receiving transducers arranged at an interval d in a direction orthogonal to the virtual measurement line B in the other side end when the center of the directional characteristic of the ultrasonic wave reaches the origin a. Arrange at the position where the magnitude of each output signal is equal,
When the transmitting transducer section is rotated, and each of the pair of receiving transducer sections receives the ultrasonic waves transmitted by the transmitting transducer section and the output signals have the same magnitude. The rotation angle of the transmitting transducer unit with respect to the virtual measurement line B is defined as a deflection angle θ, and the flow velocity in the open channel is calculated from the deflection angle θ and the value of the sound speed c of the ultrasonic wave. A method for measuring the flow velocity of a channel. 3. An output of each of a pair of receiving transducer sections is input to a differential amplifier, and a measurement point b or an output of a differential amplifier is output from a position where an output signal of the differential amplifier becomes ΔU = 0. 3. The method for measuring the flow velocity of an open channel according to claim 1, wherein the deflection angle θ is obtained from the rotation angle at which the signal becomes ΔU = 0. 4. The receiving output signal of _one receiving transducer section is U ₁ , the receiving output signal of the other receiving transducer section is U _2, and U ₂ / U ₁ is maximum or U ₁ / U. _Two
When the position of the other receiving transducer section is the measurement point b or the other receiving transducer section is coincident with the origin a, the rotation angle of the transmitting transducer section is minimized. The method for measuring the flow velocity of an open channel according to claim 1 or 2, wherein the deflection angle is θ. 5. An apparatus for measuring the flow velocity of an open channel, wherein an intersection point of an arbitrary virtual measurement line B orthogonal to the open channel with the other end of the open channel is set as an origin a, and a virtual measurement of the open channel is performed. A transmitting transducer portion disposed at one end of the straight line B, and the virtual measurement straight line B disposed at the other end.
A pair of receiving transducer sections arranged at an interval d in a direction orthogonal to the direction and receiving the ultrasonic waves from the transmitting transducer section; and the pair of receiving transducers at least one of which is displaced in the orthogonal direction. Displacement point b at the center of the directional characteristic of the ultrasonic wave at the position where the magnitude of each output signal of the transducer section becomes equal.
The deflection distance 1 is determined from the distance between the measurement point b and the origin a, and the time t required for the ultrasonic wave to reach the reception transducer section from the transmission transducer section is calculated. An arithmetic and control device for performing any or all of the measurement, the ultrasonic sound velocity c measurement, and the like, and a flow velocity measuring device for an open channel. 6. A receiving output signal of _one receiving transducer section is U ₁ , and a receiving output signal of the other receiving transducer section is U _2, and U ₂ / U ₁ is maximum or U ₁ / U. _Two
Is measured as the measurement point b and the deflection distance 1 is determined from the distance between the measurement point b and the origin a. 6. The flow velocity in an open channel according to claim 5, further comprising a calculation and control device for performing any or all of a measurement of a time t required for reaching the receiving transducer unit from the unit and a measurement of a sound speed c of the ultrasonic wave. measuring device. 7. An apparatus for measuring the flow velocity of an open channel, wherein an intersection point of an arbitrary virtual measurement line B orthogonal to the open channel with the other end of the open channel is set as an origin a, and the virtual measurement of the open channel is performed. A transmitting transducer portion rotatably disposed in one end on a straight line B, and a spacing d in the other end in a direction perpendicular to the virtual measurement line B and directing ultrasonic waves. A pair of receiving transducer sections arranged at positions where the magnitudes of the respective output signals become equal when the center of the characteristic reaches the origin a; the transmitting transducer section and the receiving transducer section; Connected to the section, to rotate the transmission transducer section,
Each of the pair of receiving transducer units receives the ultrasonic wave transmitted by the transmitting transducer unit, and the transmitting transducer with respect to the virtual measurement line B, in which the magnitude of the output signal becomes equal. The rotation angle of the
A flow rate measuring device for an open channel, comprising: an arithmetic and control device for measuring and measuring a sound speed c of an ultrasonic wave. 8. A transmitting transducer portion rotatably disposed in one end of the open channel on a virtual measurement line B, and a transmitting transducer portion in the other end thereof in a direction orthogonal to the virtual measurement line B. A pair of receiving transducers arranged with an interval d and the other receiving transducer being made coincident with the origin a; and a pair of the transmitting transducer and the receiving transducer. Connected, the transmitting transducer unit is rotated to receive the ultrasonic wave transmitted by the transmitting transducer unit. The reception output signal of _one receiving transducer unit is U ₁ , and the other is U ₁ . The reception output signal of the reception transducer unit is U _2, and the rotation angle of the transmission transducer unit with respect to the virtual measurement line B where U ₂ / U ₁ is maximum or U ₁ / U ₂ is minimum. Is measured as the deflection angle θ, and the sound speed c of the ultrasonic wave is measured. The flow velocity measuring device for an open channel according to claim 7, further comprising a calculation / control device. 9. The receiving transducer section disposed in the other end of the open channel is constituted by a number of transducer pieces arranged in a direction orthogonal to the virtual measurement line B, and each of the transducer sections is provided. 5. The method according to claim 5, wherein each of the pieces is connected to an arithmetic and control unit.
The flow velocity measuring device for an open channel according to 6, 7, or 8. 10. A transmitting transducer at one end in a water tank.
And a pair of receiving transducers arranged at a distance d in a direction orthogonal to the transmitting direction of the transmitting transducer in the other end. Section and the receiving transducer section at various positions,
Translated along the direction of the interval d, each of the pair of receiving transducer units at the various positions receives the ultrasonic wave from the transmitting transducer unit, and outputs each output signal. Are equal to U ₂₁ = U ₂₂ or the output signal U ₂₁
An output signal of the differential amplifier becomes .DELTA.U = 0 to input U ₂₂ to the differential amplifier, or the ratio of the output signals U ₁ and U ₂ each is maximum or minimum, a pair of receiving transformer du - Sa A calibration inspection method comprising: detecting a position of each of the parts and comparing the detected position with a movement amount of a corresponding transmitting transducer.