JP3953826B2 - Insertion type electromagnetic current meter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an insertion type electromagnetic velocimeter that is inserted from the outside of a pipe through which a fluid to be measured flows and measures a fluid flow velocity in the pipe.
[0002]
[Prior art]
There are current meters and flow meters that measure using water hydrants and air valves as measuring devices for water leakage and stagnant water surveys in water supply piping networks.
[0003]
Typical examples of these devices include an ultrasonic type and an electromagnetic type. Examples of the ultrasonic type include those disclosed in Japanese Patent Laid-Open Nos. 3-231155 and 6-81378. . Examples of the electromagnetic type are disclosed in, for example, Japanese Utility Model Laid-Open No. 60-86922 and Japanese Patent Laid-Open No. 60-179613.
[0004]
[Problems to be solved by the invention]
The ultrasonic type can be measured by attaching a sensor to the outside of the pipe, so it has the advantage of being able to measure without putting foreign matter in the water pipe, but it is difficult to measure the micro flow velocity, and the scale is attached to the pipe. In some cases, it may be difficult to detect. In addition, when performing measurement using a fire hydrant, there are many fire hydrant pits that are not exposed because the water pipe is buried in the earth and sand. In order to solve this problem, an insertion type ultrasonic flowmeter that is inserted into the tube and measured has been developed. However, it is necessary to consider the installation position of the transmitter using a small opening such as a fire hydrant. Moreover, the structure becomes complicated.
[0005]
On the other hand, since the electromagnetic type cannot install an electromagnetic flow meter by cutting a pipe, an insertion type electromagnetic current meter that measures by inserting a flow rate sensor into the pipe from a fire hydrant or an air valve has been used. It was.
[0006]
Electromagnetic anemometers are likely to be complicated in structure because they are inserted into piping, and Karman vortices are generated in the inserted sensor part, and the sensor part vibrates due to the reaction force. The distribution was not stable and the measurement accuracy was reduced. A detection sensitivity of 10MM / S or less is desired as an anemometer for soundness evaluation of water supply pipe networks, but there is no anemometer that meets such requirements, and a more sensitive anemometer is awaited.
[0007]
An object of the present invention is to solve the above-described conventional problems and provide a highly sensitive anemometer suitable for the purpose of evaluating the soundness of a water distribution pipe network.
[0008]
[Means for Solving the Problems]
The feature of the present invention in the above object includes a sensor unit that measures the flow velocity of the fluid to be measured in the pipe, and a support unit that includes a transmission line that transmits a measurement value obtained by the sensor unit to the outside. In the insertion type electromagnetic velocimeter that inserts the sensor part into the pipe from the opening of the pipe and measures the flow velocity of the fluid to be measured, the sensor portion has a flow direction of the fluid to be measured in the sensor portion housing. It has a measurement flow path penetrating in parallel with the.
[0009]
Preferably, the measurement flow path further includes a magnetic field generation unit including a coil and a magnetic pole, and further includes a pair of magnetic pole plates having a length covering at least the magnetic field generation unit and a side surface of the measurement flow path. That is.
[0010]
Further preferably, the sensor section housing has a cross-sectional shape orthogonal to the insertion direction thereof being streamlined with respect to the flow direction of the fluid to be measured, and the measurement flow path is the center of the insertion axis of the sensor section. It is formed on the shaft.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings. Figure 1 shows the basic configuration of a hydraulic and water quality monitoring system installed in an underground pit on a fire hydrant provided in the middle of a pipeline network in order to monitor the soundness of the water distribution pipeline network. FIG.
[0012]
Fire hydrants 2 provided in the middle of the water supply pipe 1 buried underground are arranged at predetermined intervals in the pipeline network, and the flow rate, flow direction, water quality, temperature, pressure, etc. of the tap water 3 It is suitable for monitoring various information. In particular, the underground fire hydrant pit 4 is suitable for continuous monitoring by installing a measuring instrument for a predetermined period.
[0013]
The fire hydrant 2 has an adapter to which a fire hose can be connected in the event of an emergency such as a fire. However, the present invention provides a monitoring system for remodeling the adapter and attaching various sensors to continuously monitor the various information for a predetermined period. .
[0014]
In addition to the hose connection port 6, the adapter 5 is provided with a sensor insertion port 7, and a velocimeter sensor 9 is inserted through the upper end opening 8 of the sensor insertion port 7 and held at the tip thereof. 10 reaches the inside of the water distribution pipe 1 and senses the flow rate of the tap water 3. The cable 11 is connected to the anemometer sensor 10 through the anemometer detector 9 and the support rod 14, and the measurement signal of the anemometer sensor 10 is transmitted to the anemometer converter 12 via the cable 11. The calculated value corresponding to the flow velocity is calculated.
[0015]
A data logger 13 that stores flow velocity measurement data for a predetermined period is built in the flow velocity meter conversion unit 12. Further, the data logger 13 has a function of storing various external information (electrical signals).
[0016]
On the other hand, the support rod 14 holding the anemometer sensor 10 is formed with a sampling port 16 for guiding the tap water 3 in the distribution pipe 1 to the outside of the pipe. A flow path 15 passing through the support rod 14 is connected, and the tap water introduced from the sampling port 16 is guided out of the flow meter detection unit 9. At this time, a water pressure sensor 17 and a sampling tube 18 are attached to the flow meter detection unit 9. The measurement signal of the water pressure sensor 17 is transmitted to and stored in the data logger 13 built in the current meter conversion unit 12 via the cable 19. Further, the tap water 3 flowing in the sampling tube 18 is guided to the multi-item water quality meter 20.
[0017]
The multi-item water quality meter 20 is provided with a residual chlorine sensor 21, a conductivity sensor 22 and the like, and a water temperature sensor 23 is provided in the sampling tube 18 to continuously or intermittently adjust the water quality of the tap water 3. To monitor. The outputs of these sensors are guided to the calculation unit 24 and are calculated and output as measured values.
[0018]
The output measurement signal is transmitted to and stored in the data logger 13 built in the velocimeter conversion unit 12 via the cable 25.
[0019]
On the other hand, a pressure reducing valve 26 is connected in the middle of the sampling tube 18 to keep the pressure of the tap water 3 led to the water quality meter constant and to keep the sampling flow rate constant.
[0020]
The tap water 3 that has passed through the multi-item water quality meter 20 is drained from the water outlet 27 into the fire hydrant pit 4. Since the drainage is an underground seepage type, the amount of water used is limited (20 cm ³ / min or less), so a small multi-item water quality meter using a microcell made by micro-processing a silicon wafer is suitable for the water quality meter to be used. . (For example, JP-A-2000-88841 shows an example thereof.)
Further, the battery unit 28 supplies power to the velocimeter conversion unit 12 and the multi-item water quality meter 20 via the cables 29 and 30.
[0021]
In such a continuous monitoring device, the flow rate, flow direction, water quality, water temperature, and water pressure are continuously monitored for a predetermined period, and the measured values are stored in the data logger 13. The data stored at this time is taken up by the portable personal computer 31 after the measurement is completed, and the data is sent to the upper management computer 33 via the medium 32 such as a communication line or a floppy disk for centralized management. Further, the data in the data logger 13 can be continuously monitored by the management computer 33 via a wireless or public telephone network. In this case, the data logger 13 incorporates a transmission function of a specific low-power radio or a mobile phone, and transmits it as a radio signal 35 to the outside of the pit via the antenna 34. At this time, the antenna is arranged in the vicinity of the keyhole (not shown) of the lid of the fire hydrant pit and transmits radio waves to the ground.
[0022]
By performing measurements at the fire pit pit 4 at a number of locations at the same time, it is possible to monitor the behavior of the tap water 3 in the distribution pipeline network, and to prevent leakage, stagnant water, deterioration of water quality, etc. The database can be used for proper arrangement and maintenance.
[0023]
Next, the details of the insertion-type electromagnetic velocimeter sensor unit of the present invention will be described with reference to FIGS. 2 is an external view of the anemometer sensor 10, FIG. 3 is a cross-sectional view of the anemometer sensor 10, and FIG. 4 is a diagram showing a state when a magnetic field is generated in the cross-sectional view of FIG.
[0024]
First, in FIG. 2, the direction of the arrow 101 indicates the flow of the tap water 3 that is the fluid to be measured, and branches as indicated by the arrow 102 when reaching the vicinity of the streamlined velocity sensor 10.
[0025]
A part of it flows inside the through hole 103 having an elliptical cross section on the central axis of the flow velocity sensor 10, and the other flows along the outer surface of the streamline flow velocity sensor 10 and merges again on the downstream side. To do.
[0026]
The through hole 103 is arranged symmetrically with respect to the central axis in the insertion direction of the velocimeter sensor 10 even in the direction of flow of the tap water 3 and the direction orthogonal thereto, and is formed so that the insertion direction becomes a long axis. It is. Further, the outer peripheral portion of the anemometer sensor 10 is formed of metal or synthetic resin, but the inner surface of the through hole 103 is covered with an insulator such as synthetic resin.
[0027]
Further, the cross-sectional area of the through hole 103 occupies 10% or more of the cross-sectional area of the flow velocity sensor 10 and has a cross-sectional area sufficient to reduce Karman vortices generated on the downstream side of the flow velocity sensor 10. desirable.
[0028]
Next, description will be given with reference to FIG. Each figure of FIG. 3 shows each cross section of three orthogonal axes of FIG. FIG. 3 (1) shows a central cross section along the insertion direction of the anemometer sensor 10 of FIG. 2 and a cross section orthogonal to the flow direction 101 of the tap water 3. The outer peripheral part of the anemometer sensor 10 is covered with a casing 201 made of metal or synthetic resin.
The above-described through hole 103 is formed of an insulating material such as a synthetic resin at the lower center of the anemometer sensor 10, and the tap water 3 flows inside thereof.
[0029]
A pair of magnetic pole plates 206 and 207 made of a magnetic material are disposed on both side surfaces of the through hole 103. In addition, a coil 208 and a magnetic pole 209 for generating a magnetic field are held above the magnetic pole plates 206 and 207. By exciting the coil 208 with a square-wave excitation current, an alternating magnetic field 210 having a substantially uniform magnetic flux density is formed between the two magnetic pole plates, as shown in FIGS. The sensor shape of FIG. 4 is the same as FIG.
[0030]
On one side or both sides of the long-axis side surface of the through hole 103, a plurality of electrodes 202, 203, 204 are respectively insulated and exposed on the inner surface 205 of the through hole, and arranged so as to come into contact with the liquid. The electrodes 202, 203, and 204 are arranged so as not to contact the magnetic pole plate 207. That is, the magnetic pole plate 207 is provided with a clearance hole for passing the electrode.
[0031]
As a result, since tap water, which is a conductive fluid, moves perpendicular to the magnetic field, an electromotive force is generated according to Faraday's law of electromagnetic induction. This is the principle by which the electromotive force is detected by the electrodes 202 and 204 to obtain a voltage signal proportional to the flow velocity. On the other hand, the electrode 203 is a ground electrode and serves as a reference potential when the voltage signal is amplified.
[0032]
Next, FIG. 3 (2) shows a cross section at the center cross section along the insertion direction of the anemometer sensor 10 of FIG. 2 and parallel to the flow direction 101 of the tap water 3. (Cross-sectional view orthogonal to FIG. 3 (1)) The shape of the casing 201 is formed so as to be line-symmetric with respect to the central axis. In addition, the components 202 to 209 in the casing 201 described with reference to FIG. 3A are also arranged on the central axis of the casing 201 as illustrated in FIG. It is desirable that the shape of each component is axisymmetric with respect to the central axis of the housing 201. The height h of the flow path 103 is larger than twice the width w shown in FIG. 3 (1) so that a large electromotive force can be obtained with respect to the pipeline area, and the length L is the height. The shape is longer than ½ times h and is suitable for stabilizing the flow and potential distribution.
[0033]
FIG. 3 (3) is a view of FIG. 3 (2) as seen from below the cross section along the central axis of the flow path 103. (Cross section perpendicular to Fig. 3 (1) and (2))
The cross-sectional outer shape of the housing 201 is streamlined, and a through hole 103 is provided in the center along the flow of the fluid to be measured. The shape is formed so as to be line symmetric with respect to both central axes of the casing 201, and the structure has the same characteristics with respect to the fluid flow direction.
[0034]
Next, description will be made with reference to FIG. FIG. 5 is a cross section orthogonal to the flow direction of the hydrant mounting portion of the water distribution pipe 1. The flow velocity sensor 10 attached to the tip of the support rod 14 is inserted into the water distribution pipe 1 from above, and the stoppers 503 held in a plurality of guide portions 501 and 502 provided on the side surfaces of the flow velocity sensor 10 are provided. Press against the inner surface of the water pipe 1. At this time, if the length of the stopper 503 is selected to be a predetermined dimension, the through hole 103 of the flow rate sensor 10 can be aligned with the center of the water distribution pipe 1.
[0035]
In this structure, since the inside of the through-hole 103 is blocked from the outer flow, it is difficult to be disturbed by the outer flow, and the potential of the electromotive force is obtained by being electrically and magnetically shielded by the magnetic pole plates 206 and 207. The advantage is that the distribution is stable. Further, if the casing 201 is formed of a conductor such as metal, the electrical shield becomes more complete, and improvement in the stability of characteristics can be expected. When the housing 201 is formed of a conductor, the grounding electrode 203 can be omitted and the housing 201 can be used as a substitute for the grounding electrode.
[0036]
In addition, the generation of Karman vortex is small and the anemometer sensor 10 is less likely to vibrate, and the through hole 10 is formed in an oval shape, so that the magnetic flux density can be increased and the electromotive force between the electrodes can be increased. There are advantages such as high signal.
[0037]
【The invention's effect】
According to the present invention, the following effects can be expected.
1. Since the fluid to be measured also flows inside the current sensor, the Karman vortex is hardly generated and the current sensor does not vibrate.
2. Since the fluid to be measured flows inside the anemometer sensor, the flow of the fluid to be measured in the vicinity of the electrode is unlikely to be disturbed.
3. Inside the through hole through which the fluid to be measured flows, a uniform and stable magnetic field distribution can be expected by two magnetic pole plates facing each other.
4). Since the long axis is a direction in which the shape of the through hole is orthogonal to the magnetic field, an electromotive force between the electrodes is large and a flow rate signal having a large S / N ratio can be expected.
5). Since the anemometer sensor is small and streamlined and has a through hole inside, the sensor position is stable in the water pipe with little fluid resistance.
6). Since the casing and the flow path are symmetrical with respect to the central axis, the flow velocity measurement with the same characteristics can be expected for the flow in both forward and reverse directions.
7). As described above, an electromagnetic current meter with high sensitivity and stable measurement signal can be realized.
8). Adjustment of the insertion position of the flow rate sensor is easy due to the adjustable stopper.
9. Measurements of flow velocity, water quality, water temperature, water pressure, etc. can be performed at the same time, and rich hydraulic water quality data can be obtained.
Ten. The workability of hydraulics and water quality measurement is improved.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram showing an entire system according to an embodiment of the present invention;
FIG. 2 is an external view of a flow rate sensor used in the embodiment.
FIG. 3 is a cross-sectional view of the flow rate sensor in three orthogonal directions.
4 is an explanatory diagram of magnetic flux distribution in FIG. 3; FIG.
FIG. 5 is a short-axis cross-sectional view of a water pipe.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Water distribution pipe, 3 ... Fluid, 7 ... Sensor insertion port, 9 ... Current meter detection part, 10 ... Flow velocity sensor, 202, 203, 204 ... Electrode, 206, 207 ... Magnetic pole plate.

Claims (8)

A sensor unit that measures a flow velocity of the fluid to be measured in the pipe, and a support unit that has a transmission line that transmits a measurement value obtained by the sensor unit to the outside, and the sensor is inserted into the pipe from the opening of the pipe In the insertion type electromagnetic velocimeter for measuring the flow velocity of the fluid to be measured,
The sensor unit, while the housing of the sensor unit, have a measured flow path through in parallel to the direction of flow of the fluid to be measured,
Provided with magnetic field generating means comprising a coil and a magnetic pole on the upper part of the measurement flow path, and further comprising a pair of magnetic pole plates having a length covering at least the magnetic field generation means and the side surface of the measurement flow path,
An insertion type electromagnetic velocimeter characterized in that a pair of electrodes for detecting a flow velocity and a ground electrode grounded to a fluid are arranged on the inner wall of the measurement flow path . In claim 1,
The pair of electrodes for detecting the flow velocity and the ground electrode are arranged in three rows along the insertion axis of the sensor unit, and the center electrode is the ground electrode. Electromagnetic current meter. In claim 1,
The housing of the sensor unit has a cross-sectional shape orthogonal to the insertion direction, which is streamlined with respect to the direction in which the fluid to be measured flows,
An insertion-type electromagnetic velocimeter formed symmetrically with respect to a central axis in a direction in which the fluid to be measured flows and a central axis in a direction orthogonal to the direction in which the fluid to be measured flows. In claim 1,
The length L of the measurement channel in the direction of flow of the fluid to be measured is 0.5 times or more the height h of the measurement channel. In claim 4 ,
The insertion type electromagnetic velocimeter characterized in that the height h of the measurement channel is at least twice the width W of the surface orthogonal to the flow direction of the fluid to be measured in the measurement channel. In claim 1,
The insertion type electromagnetic velocimeter is characterized in that a cross-sectional area of the measurement flow path is formed to be 10% or more of a cross-sectional area of the sensor unit housing. In claim 1,
An insertion type electromagnetic velocimeter characterized in that an inner wall of the measurement channel is covered with an insulator. In claim 1,
An insertion-type electromagnetic velocimeter comprising a stopper member disposed along an insertion direction of the sensor unit and capable of adjusting a position with respect to the insertion direction on an outer wall of a housing of the sensor unit.

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