JP2002162268A - Ultrasonic flow rate measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve flow rate measuring precision in an ultrasonic flow rate measuring device. SOLUTION: The ultrasonic flow rate measuring device is provided with a pair of sensor lifting and lowering units 3A, 3B. Each sensor lifting and lowering unit 3A, 3B is provided with an ultrasonic sensor 2A, 2B and a lifting and lowering mechanism 6 lifting and lowering the ultrasonic sensors 2A, 2B in the water depth direction. The opposite direction of the ultrasonic sensors 2A, 2B makes an angle in the direction of the flow of an open water passage 1 in plan view. A drive and control device 7b controlling the lifting and lowering mechanism 6 of each sensor lifting and lowering unit 3A, 3B is provided so that the ultrasonic sensors 2A, 2B of each sensor lifting and lowering unit 3A, 3B are at the same water depth position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic flow rate measuring device for measuring a flow rate in an open channel such as a river, a canal, an irrigation channel and the like.

[0002]

2. Description of the Related Art As a flow rate measuring device for a river, a canal, an irrigation canal or the like (open channel), an apparatus using an ultrasonic sensor capable of transmitting and receiving ultrasonic waves (an ultrasonic flow measuring device) is known. . This ultrasonic flow measurement device uses the property that the sound velocity in water is affected by the flow velocity, and the sound velocity increases when the velocity in the direction of ultrasonic propagation is positive, and decreases when the velocity is negative. are doing.

[0003] As this type of ultrasonic flow measuring device,
For example, there is known an apparatus having a pair or two pairs of ultrasonic sensors arranged to face each other at the same water depth on both sides of an open channel. This flow rate measurement device measures the change in ultrasonic arrival time or the change in frequency from one shore-side ultrasonic sensor to the other shore-side ultrasonic sensor due to the flow velocity, and determines the ultrasonic wave propagation from these changes. The average flow velocity in the route is estimated, and the total flow rate of the open channel is estimated based on the estimated value.

Also, a plurality of pairs of ultrasonic sensors are arranged so as to face each other at a plurality of water depth positions on both sides of the open channel, and an ultrasonic wave for estimating the total flow rate of the open channel from the change in the ultrasonic arrival time or frequency. 2. Description of the Related Art There are known flow rate measuring devices.

[0005] Further, as another flow measuring device,
A method of measuring the flow velocity by detecting the frequency change due to the Doppler effect of the ultrasonic wave reflected by a scatterer such as a floating substance (ADCP: Acoustic doppler current pro
file), and a flow rate measuring device that estimates a flow rate from a measured value of water surface velocity by a radio current meter.

[0006]

However, the above-mentioned conventional flow rate measuring apparatus has the following problems. First, in the case of an ultrasonic flow rate measuring device provided with a pair of ultrasonic sensors at the same water depth position, the flow rate is estimated from the flow velocity at a single water depth position based on an estimation formula. That is, in this flow rate measuring device, since there is no flow velocity distribution in the water depth direction, the flow rate in the open channel is estimated, and thus a large error may occur. On the other hand, there has been known a method of selectively using or changing a flow rate estimation formula according to a water level. However, even in this case, it is difficult to obtain a practically sufficient flow rate measurement accuracy.

Next, in the case of a flow measuring device having a plurality of pairs of ultrasonic sensors arranged at the plurality of water depth positions, it is necessary to increase the depth positions at which the flow velocity is measured in order to obtain sufficient flow measurement accuracy. Therefore, it is necessary to install a large number of ultrasonic sensors, and the apparatus becomes expensive. In addition, the ultrasonic sensor may be positioned above the water due to a decrease in the water level and may become unusable, so that the ultrasonic sensor cannot be effectively used. Further, the water depth changes the depth position of the ultrasonic sensor due to the fluctuation of the water level, and the flow rate measurement accuracy changes.

[0008] In the case of a flow rate measuring apparatus to which the above-mentioned ADCP is applied, a bridge-like structure spanning an open channel is provided.
It is necessary to move a moving body having a plurality of ultrasonic sensors on the bridge-like structure. Therefore, this flow measuring device requires large-scale equipment, is not suitable for steady or continuous flow measurement, and is not suitable for a flood measurement in which the need for flow measurement is particularly high.

Further, the flow rate measuring device using the above-mentioned radio current meter cannot obtain sufficient measurement accuracy. In particular, the flow rate measuring device is strongly affected by the wind in principle, so that the accuracy is further reduced when the wind is strong.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the conventional flow rate measuring apparatus, and has a practically sufficient flow rate measuring accuracy and is relatively inexpensive and suitable for steady flow rate measurement. It is an object to provide a simple ultrasonic flow measurement device.

[0011]

In order to solve the above problems, the present invention comprises at least one pair of ultrasonic sensors arranged on both banks of an open channel, and transmits and receives signals between these ultrasonic sensors. An ultrasonic flow rate measuring device that measures the flow velocity in the ultrasonic propagation path based on the propagation time of the ultrasonic wave to be calculated, and calculates the flow rate of the open channel based on the measured value, and one ultrasonic sensor and And an elevating mechanism for raising and lowering the ultrasonic sensor in the depth direction.The ultrasonic sensors are arranged on both banks of the open channel so that the facing direction of the ultrasonic sensor forms an angle with the flow direction of the open channel in plan view. At least a pair of sensor elevating units, and a control unit that controls an elevating mechanism of each sensor elevating unit so that the ultrasonic sensors of the sensor elevating units are at the same water depth position. There is provided an expression flow rate measuring device.

More specifically, the ultrasonic sensors of each sensor elevating unit are moved to a plurality of measurement water depth positions, and the propagation times of ultrasonic waves between the ultrasonic sensors at each measurement water depth position are measured. The flow rate of the open channel is calculated based on the flow rate.

In the ultrasonic flow rate measuring apparatus of the present invention, at least one pair of sensor elevating units having an elevating mechanism for elevating and lowering the ultrasonic sensors in the water depth direction, and the ultrasonic sensors of each sensor elevating unit are located at the same water depth position. Since the control unit controls the lifting mechanism as described above, the flow rate distribution in the cross section of the open channel can be measured, and the flow rate can be measured with high accuracy. Further, there is no need to provide a plurality of pairs of ultrasonic sensors at a plurality of water depth positions, and the structure is simple, relatively inexpensive, and maintenance is easy. Furthermore, since large-scale facilities such as bridge-like structures that are bridged over the open channel are not required, steady and continuous flow measurement including the time of flood occurrence is possible.

In particular, it is preferable to set the plurality of measured water depth positions according to the maximum water depth of the open channel.

More specifically, it is preferable to calculate the interval between the measured water depth positions based on the following equation.

[0016]

Δd ′ = (n × Δd + δ) / n ′, where D: maximum water depth d0: width of water-side dead zone d1: width of bottom dead zone Δd ′: interval of measured water depth Δd: transmitted by ultrasonic sensor The width of the ultrasonic wave in the depth direction n: n = int (D− (d0 + d1) / Δd) int (A) is an integer value of the real number A after truncation below the decimal point n ′: n ′ = n + 1 δ: δ = D − (D0 + d1 + n × Δd)

In this case, since the flow rate distribution can be measured in the entire cross section of the open channel excluding the water surface side and the bottom dead zone, more accurate flow rate measurement is possible.

Further, the positions of 20% and 80% of the maximum water depth in the depth direction from the water surface may be set as the measured water depth positions.

On the other hand, a single measured water depth position is set according to the maximum water depth of the open channel, and the total flow rate of the open channel is determined based on the propagation time of the ultrasonic wave between the ultrasonic sensors measured at this measured water depth position. It may be calculated. Normally, the flow distribution in the cross section of the open channel has low flow velocity near the water surface and near the bottom,
The flow velocity at a position of about 60% in the depth direction from the water surface is close to the average flow velocity. Therefore, when setting a single measured water depth position, it is preferable that the position of 60% of the maximum water depth from the water surface side be the measured water level position.

The method for measuring the maximum water depth is not particularly limited. For example, a water surface position is detected based on a change in the level of multiple reflection of ultrasonic waves transmitted by the ultrasonic sensor, and a reflecting member disposed at the bottom of an open channel corresponding to at least one of the sensor elevating units. Provided, the bottom of the open channel is detected based on the reflection of the ultrasonic wave transmitted by the ultrasonic sensor by this reflecting member, and based on the detected water surface position and the bottom of the open channel, the maximum water depth is estimated. Is also good.

Further, a water surface position is detected based on a change in the level of multiple reflection of ultrasonic waves transmitted by the ultrasonic sensor, and a bottom of an open channel is detected from a descent limit of the elevating mechanism.
The maximum water depth may be estimated based on the detected water surface position and the bottom of the open channel.

Further, the maximum water depth may be measured by this water level gauge. The maximum water depth may be confirmed by visually reading the scale of the water level scale.

One ultrasonic sensor of the pair of sensor elevating units may be of a responder type. In this case, there is no need to lay a control cable across the open channel, which is suitable when the open channel is wide.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention shown in the drawings will be described in detail. The ultrasonic flow rate measuring apparatus according to the embodiment of the present invention shown in FIGS. 1 to 3 includes one ultrasonic sensor 2A, 2B, and a pair of sensor elevating units arranged on both banks of the open channel 1. 3A and 3B, a central monitoring room 4, and reflectors 5A and 5B.

Since the sensor elevating units 3A and 3B have the same structure, one sensor elevating unit 3A will be described below. As shown in FIGS. 2 and 3, the sensor elevating unit 3A includes an elevating mechanism 6 and an on-site control panel 7 for elevating and lowering the ultrasonic sensor 2A in the depth direction.

A maintenance deck 9 protruding from the shore of the open channel 1 onto the water surface S is provided, and the maintenance deck 9 is provided with an elevating mechanism 6. The elevating mechanism 6 includes an elevating rod 10 that penetrates a distal end portion of the maintenance deck 9 and extends vertically. The elevating rod 10 is a cylindrical body having an elliptical cross section, and the lower end side thereof accommodates the ultrasonic sensor 2A.

As shown in FIG. 4, the ultrasonic sensor 2A
A sensor main body 2a including a piezoelectric element for generating ultrasonic waves,
And a housing 2b in which the sensor main body 2a is accommodated. The ultrasonic sensor 2A is disposed so as to form a predetermined angle (45 ° in the present embodiment) with respect to the flow direction F of the open channel 1 in plan view. Therefore, as shown in FIG. 1, the ultrasonic sensors 2 of each of the sensor elevating units 3A and 3B
In A and 2B, these facing directions (the direction of the ultrasonic wave propagation path U) form a predetermined angle with respect to the flow direction F of the open channel 1 in plan view. The cable 50 connected to the ultrasonic sensor 2 </ b> A is inserted into the inside of the lifting rod 10, and is connected from the upper end side of the lifting rod 10 to a later-described converter 7 a of the on-site control panel 7 via the cable reel 11.

The lifting rod 10 is provided with a pair of racks 12 extending in the axial direction thereof, and these racks 12 are provided with a pair of pinions 13 on the maintenance deck 9.
(Only one pinion is shown in FIG. 2). An elevating motor 14 as an electric motor is disposed on the maintenance deck 9, and a pinion 13 is provided.
Is connected to the elevating motor 14 via a power transmission mechanism including a drive shaft 16 and a gear (not shown). Therefore, when the elevating motor 14 rotates, the elevating rod 10 moves up or down according to the rotation direction, and the water depth position of the ultrasonic sensor 2A housed at the lower end of the elevating rod 10 changes. The elevating motor 14 is connected by a cable 51 to a drive / control device 7b of the on-site control panel 7, which will be described later.

The maintenance deck 9 is provided with a counterweight 17 for ensuring a weight balance and a reinforcing frame 18.

The on-site control panel 7 includes a converter 7a for controlling the ultrasonic sensor 2A, that is, controlling transmission and reception of ultrasonic waves. The on-site control panel 7 includes a drive / control device (control section) 7b connected to a central control panel 4a to be described later by a cable 52. The on-site control panel 7 drives and controls the elevating mechanism 6, and controls the central control panel 4a.
Communication with the server. Further, the on-site control panel 7 includes a power supply device 7b for supplying power to the converter 7a and the drive / control device 7b.

On the other hand, the central monitoring room 4 has a central control panel 4
a, and a personal computer (PC) 4b for the operator to operate the central control panel 4a. The central control panel 4a drives and stops the elevating / lowering motor 14 and issues a command to the ultrasonic sensors 2A and 2B to each of the sensor elevating units 3 in accordance with a flow measurement mode described later.
Output to the on-site control panel 7 of A, 3B. Also, the ultrasonic sensors 2A, 2B of the sensor lifting units 3A, 3B
A signal indicating transmission and reception of ultrasonic waves at the
a and the central control panel 4a via the drive / control device 7b.
Is input to Further, a signal indicating the position (height) of the ultrasonic sensors 2A, 2B is input from the drive / control device 7b to the central control panel 4a.

The reflectors 5A and 5B are installed on the bottom 1a of the open channel 1, and when the lower end of the lifting rod 10 reaches the bottom 1a of the open channel 1 (the ultrasonic sensor 2), as shown in FIG.
When A and 2B are at the deepest water depth positions), they face the ultrasonic sensors 2A and 2B. The reflection plates 5A and 5B are
The ultrasonic sensors 2A and 2B are disposed close to the ultrasonic sensors 2A and 2B so that there is no object between them and the ultrasonic sensors 2A and 2B.

Next, the operation of the ultrasonic flowmeter will be described. As described above, each sensor elevating unit 3
The lifting rods 10 of A and 3B are driven by a lifting motor 14 to move up and down, and the lifting motor 14 is controlled by a drive / control device 7 b of a site control panel 7. The drive / control device 7b of each of the sensor elevating units 3A and 3B raises and lowers the elevating rod 10 according to a command from the central control panel 4a.
As shown schematically in FIG. 5, the central control panel 4a and the drive / drive control device 7a move the lifting rod 10 so that the ultrasonic sensors 2A and 2B of the sensor lifting units 3A and 3B maintain the same water depth position. Raise and lower.

The ultrasonic flow rate measuring apparatus of the present embodiment
Flow measurement can be performed in various modes (first and second modes). Among these modes, the first mode is a mode in which the flow velocity distribution is measured in almost the entire cross section of the open channel 1 and the flow rate is calculated based on the measured flow velocity distribution. On the other hand, the second
The mode is a mode in which the flow velocity is measured at one or two measured water depth positions according to the maximum water depth of the open channel, and the flow rate is calculated based on the measured flow velocity. The mode can be selected by operating the PC 4b in the central monitoring room 4.

First, the first mode will be described with reference to the flowchart of FIG. In step S1, water level detection (detection of the maximum water depth D) is executed. In this water level detection, the ultrasonic sensors 2A and 2B are lowered toward the bottom 1a of the open channel 1 from a state where the ultrasonic sensors are located in the air above the water surface S. Further, the ultrasonic sensors 2A and 2B continuously transmit ultrasonic waves, and the ultrasonic sensor 2 that transmits the ultrasonic waves.
Based on the ultrasonic waves received by A and 2B themselves, the position of the water surface and the bottom 1a of the open channel 1 are detected. Hereinafter, detection of the water surface S and the bottom 1a of the open channel 1 will be described using the ultrasonic sensor 2A as an example.

The detection of the water surface position is performed by using multiple reflection of the ultrasonic wave generated by the sensor main body 2a by the housing 2b.
As shown in FIGS. 7 and 8, when the ultrasonic sensor 2A emits an ultrasonic wave (pulse 20), the inside of the housing 2b (strictly speaking, the sensor main body 2a and the housing 2b), a pulse group 21 due to the multiple reflection is measured by the ultrasonic sensor 2A.

When the ultrasonic sensor 2A is at the position B in FIG. 5, that is, when the ultrasonic sensor 2A is underwater, the detection signal level of the pulse group 21 due to multiple reflection is very low as shown in FIG. . This is because the level of multiple reflections is extremely small because the transmittance of ultrasonic waves in water is high. On the other hand, when the ultrasonic sensor 2A is at the position A in FIG. 5, that is, when the ultrasonic sensor 2A is in the air, as shown in FIG. Sensor 2A
Is higher than when underwater. This is because, unlike underwater, in the case of in the air, almost total reflection occurs.

In this embodiment, the judgment reference level Vc is set, and when the detection signal level of the pulse group 21 exceeds the judgment reference level Vc, it is judged that the ultrasonic sensor 2A is in the air, and the judgment is made below. When the ultrasonic sensor 2
It is determined that A is in the water. Further, it is determined that the position of the ultrasonic sensor 2A when the detection signal level changes from a state exceeding the determination reference level Vc to a state falling below the determination reference level Vc is the water surface position. These determinations are made by the central control panel 4a.

On the other hand, the bottom 1a of the open channel 1 is detected by detecting the ultrasonic wave reflected by the reflector 5A. That is, when the ultrasonic sensor 2A descends to a position (position C in FIG. 5) facing the reflecting plate 5A, as shown in FIG. 9, the ultrasonic wave (pulse 2) transmitted from the ultrasonic sensor 2A
3) is reflected by the reflecting plate 5B, and the reflected ultrasonic pulse 24 is measured by the ultrasonic sensor 2A. In the present embodiment, when the pulse 24 is measured, it is determined that the ultrasonic sensor 2A has reached the bottom 1a of the open channel 1. This determination is made by the central control panel 4a. The central control panel 4a calculates a water level (maximum water depth D) from the water surface position detected as described above and the position of the bottom 1a of the open channel 1.

The member for reflecting the ultrasonic wave for detecting the bottom 1a of the open channel 1 is not limited to the above-mentioned reflecting plate, but is opposed to the ultrasonic sensors 2A and 2B which have reached the descent limit. Any member may be used as long as it is disposed relatively close to the sound wave sensors 2A and 2B.

Next, the measured water level position P is determined in step S2 in FIG. The spread Δd of the ultrasonic waves transmitted by the ultrasonic sensors 2A and 2B in the depth direction is determined depending on the ultrasonic sensor to be used in a device-dependent manner. On the water surface S side, there is a region in the water depth direction (water surface side dead zone) where flow velocity measurement is impossible due to the irregular reflection of ultrasonic waves. Similarly, the bottom 1a of the open channel 1
There is also a region (bottom dead zone) in the water depth direction on which the flow velocity measurement is impossible due to the irregular reflection of the ultrasonic wave. The width d0 of the water-side dead zone and the width d1 of the bottom dead zone are also predetermined.

Here, when Δd is the distance between the measured water level positions P (movement intervals of the ultrasonic sensors 2A and 2B), if the following equation is satisfied, the flow velocity for the entire cross section of the open channel 1 is obtained. Can be measured.

[0043]

D = d0 + n × Δd + d1, where n is an integer

Normally, however, when the above-mentioned Δd is set to the interval between the measured water level positions P, there is a region in the water depth direction where the flow velocity cannot be measured by the width δ as shown in FIG. That is, in general, the following relationship is established between the maximum water depth D, the interval Δd between the measured water level positions, and the dead zone widths d0 and d1.

[0045]

D = d0 + n × Δd + d1 + δ

In this embodiment, based on the following equation, FIG.
As shown in (2), the interval Δd ′ between the measured water level positions P where there is no region in the water depth direction where the flow velocity cannot be measured is set.

[0047]

Δd ′ = (n × Δd + δ) / n ′, where D: maximum water depth d0: width of water-side dead zone d1: width of bottom dead zone Δd ′: interval of measured water depth Δd: transmitted by ultrasonic sensor The width of the ultrasonic wave in the depth direction n: n = int (D− (d0 + d1) / Δd) int (A) is an integer value of the real number A after truncation below the decimal point n ′: n ′ = n + 1 δ: δ = D − (D0 + d1 + n × Δd)

The measured water level position P is determined by the distance Δd ′, the width d0 of the water-side dead zone and the width d1 of the bottom dead zone.

Next, in step S3 of FIG. 6, the flow velocity at each measured water level position P determined as described above is measured. Specifically, as shown in FIG. 10, one ultrasonic sensor 2A transmits an ultrasonic pulse 25, and at the same time, the other ultrasonic sensor 2B starts timing. And
The time until the ultrasonic sensor 2A detects the pulse 25 (ultrasonic propagation time Tu) is compared with the ultrasonic propagation time Tu ′ when the flow velocity is 0, and the ultrasonic wave is determined based on the difference ΔTu between the two. The flow velocity in the ultrasonic wave propagation path between the sensors 2A and 2B is calculated. The calculation of the flow velocity is performed by the central control panel 4a. The ultrasonic propagation time T at each measured water level position
u may be indirectly measured by a change in the frequency of the ultrasonic wave from one ultrasonic sensor 2A to the other ultrasonic sensor 2A.

The drive / control device 7b includes the ultrasonic sensor 2
A and 2B are moved to the measurement water level position P and stopped, and the flow velocity is measured. When the measurement of the flow velocity at one measurement water level position P is completed, the drive / control device 7b moves the ultrasonic sensors 2A and 2B to the next measurement water level position P, stops the measurement, and executes the flow velocity measurement. The above operation is repeated until the flow velocity is measured at all the measured water level positions P.

After measuring the flow velocity at all the measured water level positions P, the central control panel 4a is determined in step S4 of FIG.
Calculates the flow rate. Specifically, each of the measured water level positions P
The flow rate of the open channel 1 is calculated by integrating the area of the flow velocity measured with respect to the cross section of the open channel 1.

In the first mode, the flow velocity distribution is measured on the entire cross section of the open channel 1 excluding the water surface side and the bottom dead zone, and the flow rate is calculated based thereon. Is possible.

Next, the second mode will be described with reference to the flowchart of FIG. In the case of the second mode, whether the number of measured water level positions is one or two is input in advance from the PC 4B to the central control panel 4a.
First, the maximum water depth D is detected in step S11. The method of detecting the maximum water depth D is the same as in the case of the first mode (step S1 in FIG. 6).

Next, in step S12, if the number of measured water level positions is one, the process proceeds to step S13, where
If so, the process proceeds to step S14. As shown in FIG. 5, the flow velocity in the open channel 1 has a distribution in the depth direction. Normally, in this flow velocity distribution, the flow velocity is low near the water surface S and near the bottom 1a, and the flow velocity at a position about 60% of the maximum water depth D in the water depth direction from the water surface S is close to the average flow velocity. Therefore, step S1 where the measured water level position P is one place
In 3, the position of 60% of the maximum water depth D is set as the measured water level position P. On the other hand, in step S14 where the measured water level positions are two, the positions of 20% and 80% of the maximum water depth D are set as the measured water level position P.

Next, in step S15, the flow velocity at the measured water level position P set in steps S13 and S14 is measured, and based on the measured flow velocity, step S1 is performed.
In step 6, the flow rate is calculated.

Also in the case of the second mode, since the measured water level position P is set according to the maximum water depth D of the open channel 1, the flow rate can be measured with high accuracy.

As described above, the ultrasonic flow rate measuring device of the present embodiment can raise and lower the ultrasonic sensors 2A and 2B in the depth direction, so that the flow velocity at the optimum measurement depth position according to the maximum depth is determined. Measurement is possible, and flow measurement with high accuracy is possible. Further, since it is not necessary to provide a plurality of pairs of ultrasonic sensors at a plurality of water depth positions, the structure is simple, relatively inexpensive, and maintenance is easy. Furthermore, since large-scale equipment such as a bridge-like structure bridged over an open channel is not required, steady and continuous flow measurement including a flood occurrence can be performed.

The method of detecting the maximum water depth D is not limited to the above. For example, the water surface position is determined by the ultrasonic sensor 2
While the detection may be performed based on the level change of the multiple reflection of the ultrasonic waves transmitted by A and 2B, the lowering limit of the lifting rod 10 may be detected by the drive / control device 7b. In this case, the lower limit of the lifting rod 10 corresponds to the bottom 1 a of the open channel 1.

Alternatively, the maximum water depth may be measured by the water level gauge 30 (see FIG. 2), and the measured value may be input to the central control panel 4a.

Further, the maximum water depth may be confirmed by visually reading the scale of the water level scale, and the read value may be input to the central control panel 4a by the PC 4B.

The ultrasonic type flow measuring device of the above embodiment is
Although a single-pass type having a pair of sensor elevating units 3A and 3B on both sides of the open channel 1 is used, the present invention employs two pairs of sensor elevating units 3A and 3A on both sides of the open channel as shown in FIG.
The present invention is also applicable to a cross-pass type ultrasonic flow measurement device including 3B, 3C, and 3D. Note that, in this example, two pairs of sensor elevating units 3A to 3C are
Are arranged so that their facing directions (ultrasonic propagation paths U) are orthogonal to each other.

In the above embodiment, the ultrasonic sensor 2 of the sensor elevating unit 3B installed on the shore opposite to the central monitoring room 4 of the pair of sensor elevating units 3A, 3B.
A responder type ultrasonic sensor is used as B, and
The converter 7a may be replaced with a responder. When the responder-type ultrasonic sensor receives an ultrasonic wave transmitted as a trigger signal from the other ultrasonic sensor (the ultrasonic sensor 2A of the sensor elevating unit 3A), the ultrasonic sensor automatically transmits the ultrasonic wave or is driven by the responder. Various commands are transmitted to the control device 7b. If this responder-type ultrasonic sensor is used, there is no need to lay a control cable across the open channel 1, and it is particularly suitable when the open channel 1 is wide.

The ultrasonic wave transmitted as a trigger signal from the sensor lifting unit 3A may be a pulse group 27 transmitted at a predetermined interval ΔT, for example, as shown in FIG. By changing the interval ΔT and the number of pulses included in the pulse group 27, different commands can be transmitted to the sensor elevating unit 3A. The communication between the site control panel 7 and the central monitoring device 4 and the communication between the site control panels 7 may be wireless communication.

FIGS. 14 and 15 show the sensor elevating unit.
The structure shown in FIG. In this example, a maintenance deck 9 is provided on a vertically extending pile 40 driven into the bottom near the shore of the open channel 1, and the elevating mechanism 6 is installed on the maintenance deck 9. Other structures of the sensor elevating unit shown in FIGS. 14 and 15 are the same as those of the above embodiment.

The sensor elevating unit may have a structure shown in FIGS. In this example, the ultrasonic sensor 2 moves up and down along a slope 1b of the open channel 1 which is an inclined surface. That is, the guide rail 41 extends along the slope 1 b from the maintenance deck 9 installed on the shore of the open channel 1, and a moving body 42 that moves along the guide rail 41 is provided. This moving body 42
Is a plurality of wheels 42a guided by a guide rail 41
And the ultrasonic sensor 2 is built in. Also,
One end of a wire 53 is connected to the moving body 42, and the other end of the wire 53 is connected to the winding device 4 on the maintenance deck 9.
3 is connected. Further, one end of a cable 50 is connected to the ultrasonic sensor 2A.
Is connected to a field control panel 7 (see FIG. 1) via a cable reel 11. The winding device 43 is connected to the wire 5
When the moving body 42 is rotated in the direction in which the moving body 3 is sent out, the moving body 42 descends by its own weight. On the other hand, the winding device 43
Is wound, the moving body 42 moves up along the guide rail 41.

[0066]

As is apparent from the above description, the ultrasonic flow velocity measuring device of the present invention comprises at least one pair of sensor elevating units having an elevating mechanism for elevating and lowering the ultrasonic sensor in the depth direction, and each sensor elevating unit. Control unit that controls the elevating mechanism of each sensor elevating unit so that the ultrasonic sensors are at the same water depth position, it is possible to measure the flow velocity distribution over the entire cross section of the open channel, and with high accuracy Flow measurement is possible. In particular, by setting a plurality of measured water depth positions according to the maximum water depth of the open channel, the flow velocity can be measured at the optimum measured water depth position according to the optimum water depth, and the flow rate measurement accuracy can be further improved. .

Further, even when the flow rate is measured at one or two measured water depth positions, the flow rate measurement accuracy can be improved by setting the measured water depth position according to the maximum water depth of the open channel.

Further, since the pair of ultrasonic sensors of the sensor elevating unit moves up and down in the water depth direction as described above, the flow velocity can be measured at a plurality of water depth positions. There is no need to provide In this regard, the ultrasonic flow velocity measuring device of the present invention has a simple structure, is relatively inexpensive, and is easy to maintain.

Further, in the ultrasonic flow rate measuring apparatus of the present invention, large-scale equipment such as a bridge-like structure bridged over an open channel is unnecessary, so that the flow rate can be constantly and continuously measured even when a flood occurs. Flow measurement can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing an ultrasonic flow rate measuring device (single-pass type) according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a front view of the sensor elevating unit as viewed from the direction of arrow III in FIG. 2;

FIG. 4 is a sectional view taken along line IV-IV in FIG. 3;

FIG. 5 is a schematic diagram showing a cross section of an open channel and a flow velocity distribution in a water depth direction.

FIG. 6 is a flowchart for explaining the operation of the ultrasonic flow measurement device in the first mode.

FIG. 7 is a waveform diagram showing multiple reflections when the ultrasonic sensor is underwater.

FIG. 8 is a waveform diagram showing multiple reflections when the ultrasonic sensor is in the air.

FIG. 9 is a waveform diagram showing ultrasonic waves reflected by a reflector.

FIG. 10 is a waveform chart for explaining the principle of measuring the flow velocity.

FIG. 11 is a flowchart for explaining the operation of the ultrasonic flow rate measuring device in the second mode.

FIG. 12 is a schematic plan view showing an ultrasonic flow rate measuring device (cross-path type) according to another embodiment of the present invention.

FIG. 13 is a waveform diagram showing an example of control ultrasonic waves when the ultrasonic sensor of one sensor elevating unit is of a responder type.

FIG. 14 is a sectional view showing another example of the sensor elevating unit.

15A is a front view as viewed from the direction of arrow XV in FIG. 14, and FIG. 15B is a cross-sectional view taken along line XV'-XV 'in FIG.

FIG. 16 is a sectional view showing another example of the sensor elevating unit.

FIG. 17 is an enlarged view of a portion XVII in FIG. 16;

18 is a sectional view taken along line XVIII-XVIII in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Open channel 1a Bottom 1b Slope 2A, 2B Ultrasonic sensor 2a Sensor main body 2b Housing 3A, 3B, 3C, 3D Sensor lifting unit 4 Central monitoring room 4a Central control panel 4b Personal computer 5A, 5B Reflector 6 Lifting mechanism 7 Field control panel 7a Converter 7b Drive / control device 7c Power supply device 9 Maintenance deck 10 Lifting rod 11 Cable reel 12 Rack 13 Pinion 14 Lifting motor 16 Drive shaft 17 Counter weight 18 Frame 30 Water level gauge 40 Pile 41 Guide rail 42 Move Body 42a Wheel 43 Winding device

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F014 AA08 FB10 2F035 AA03 DA14

Claims (10)

[Claims] At least one pair of ultrasonic sensors disposed on both banks of an open channel is provided, and a flow velocity in an ultrasonic propagation path is determined based on a propagation time of ultrasonic waves transmitted and received between the ultrasonic sensors. And an ultrasonic flow rate measuring device that calculates the flow rate of the open channel based on the measured value, comprising: one ultrasonic sensor and a lifting mechanism for raising and lowering the ultrasonic sensor in the depth direction. And at least one pair of sensor elevating units arranged on both banks of the open channel such that the facing direction of the ultrasonic sensor is at an angle to the direction of flow of the open channel in plan view, An ultrasonic flow velocity measuring device, comprising: a control unit that controls an elevating mechanism of each sensor elevating unit so that the ultrasonic sensors are at the same water depth position. 2. The ultrasonic sensor of each sensor elevating unit is moved to a plurality of measurement water depth positions, the propagation time of ultrasonic waves between the ultrasonic sensors at each measurement water depth position is measured, and the ultrasonic wave is opened based on these measured values. The ultrasonic flow rate measuring device according to claim 1, wherein the flow rate of the water channel is calculated. 3. The ultrasonic flow rate measuring device according to claim 2, wherein the plurality of measured water depth positions are set according to the maximum water depth of the open channel. 4. The ultrasonic flow velocity measuring apparatus according to claim 3, wherein the interval between the measured water depth positions is calculated based on the following equation. Δd ′ = (n × Δd + δ) / n ′, where D: maximum water depth d0: width of water surface side dead zone d1: width of bottom dead zone Δd ′: interval of measured water depth Δd: transmitted by ultrasonic sensor The width of the ultrasonic wave in the depth direction n: n = int (D− (d0 + d1) / Δd) int (A) is an integer value of the real number A after truncation below the decimal point n ′: n ′ = n + 1 δ: δ = D − (D0 + d1 + n × Δd) 5. The maximum water depth of 20 from the water surface in the depth direction.
The ultrasonic flow velocity measuring device according to claim 3, wherein the position of% and the position of 80% are set as the measured water depth position. 6. A single measured water depth position is set according to the maximum water depth of the open channel, and the total flow rate of the open channel is determined based on the propagation time of ultrasonic waves between the ultrasonic sensors measured at the measured water depth position. The ultrasonic flow measurement device according to claim 1, which calculates. 7. A water surface position is detected based on a change in the level of multiple reflections of ultrasonic waves transmitted by the ultrasonic sensor, and is disposed at the bottom of an open channel corresponding to at least one of the sensor elevating units. A reflection member, the bottom of the open channel is detected based on the reflection of the ultrasonic wave transmitted by the ultrasonic sensor by the reflection member, and the maximum water depth is determined based on the detected water surface position and the bottom of the open channel. The ultrasonic flow rate measuring device according to any one of claims 3 to 6, wherein estimation is performed. 8. A water surface position is detected based on a change in the level of multiple reflection of ultrasonic waves transmitted by the ultrasonic sensor, a bottom of an open channel is detected from a descent limit of the lifting mechanism, and the detected water surface is detected. The ultrasonic flow rate measuring device according to any one of claims 3 to 6, wherein the maximum water depth is estimated based on a position and a bottom of the open channel. 9. The ultrasonic flow rate measuring device according to claim 3, further comprising a water level gauge, wherein the maximum water depth is measured by the water level gauge. 10. The ultrasonic flow velocity measuring device according to claim 1, wherein one ultrasonic sensor of said pair of sensor elevating units is of a responder type. .