JP2018194511A - Water level gauge for paddy fields - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple and low-cost paddy field water level gauge while measuring and controlling a paddy field water level quickly and accurately in real time. SOLUTION: This is a paddy field water level gauge for measuring the water level of stored water in a paddy field for controlling water supply and drainage to a paddy field surrounded by a shore, and houses a water level measuring unit, a signal processing unit and a measuring unit. It consists of a differential pressure measurement pressure sensor that is composed of a housing and has a diaphragm with an opening for the water level measurement unit, and a signal cable that transmits the measured value measured by the sensor to the signal processing unit. The housing has the sensor at one end. It is a paddy field water level gauge equipped with a pressure-water level conversion device and a water level data transfer device, and a signal processing unit is provided on the other end side of the hollow housing. [Selection diagram] Fig. 1

Description

  The present invention relates to a water supply / drainage system for a field, and in particular, water level control applied to paddy fields in the field affects the growth of cultivated crops, and it is quick and accurate for water level measurement that is the basis of water level control. Measurement is required. In this invention, it is related with the water level meter for paddy fields corresponding to such a request | requirement.

For field water management, which is often performed manually on site, remote control or automation is desired. In addition, water conservation through water management is also expected. In order to perform this water management appropriately, it is necessary to control both water supply and drainage to the field, and measurement of the water level that is the basis of the control is indispensable.
Furthermore, in the cultivation of paddy fields in the field, it is necessary to control the water level of the paddy fields quickly, accurately, and finely in order to supply the cultivated crops with the amount of water required in the growing process of the cultivated crops. There is a proposal to measure the water level using a water level gauge as the basis.

In order to measure the water level of stored water such as paddy fields, water level measurement using a water level gauge is generally used, and various water level gauges and measurement methods have been proposed.
For example, in Patent Document 1, a water pipe, a water supply for agriculture, a water level of a reservoir, a flow rate of a water channel, a detector installed under water, and a converter installed on the water surface are connected with a cable with a hollow pipe. An invention is disclosed that eliminates an atmospheric pressure fluctuation response delay error due to the introduction of atmospheric pressure of a connected water level gauge and prevents deterioration of sensors and electronic circuits.

The feature is the structure of the hollow pipe to be used. The first is a hollow pipe made of resin, and the pipe wall has a minute or through-hole of 1/3 to 1/10 of the inside diameter of the hollow pipe. It is further provided at equal intervals, and a ribbon-like resin is spirally wound to form a pipe. The second is that the resin hollow pipe has minute through-holes in the pipe wall, and there are inclusions of ion gas adsorbing fibers between the electric wires of the cable. Is spirally wound around a resin pipe. Thirdly, the resin hollow pipe has fine through-air holes in the pipe wall, the inclusions between the cable wires are ion gas adsorbing fibers and a desiccant, and the desiccant is in powder form, Its size is larger than the through-hole.
The fourth point is that the air blocking material is fixed to the end of the cable so that the air does not enter the cable with the hollow pipe.

Further, Patent Document 2 discloses a throw-in type water level meter in which a detector installed under water and a converter installed on the water surface or a converter via a relay box are connected by a cable with a hollow pipe. The invention discloses an invention that eliminates measurement errors by using a gas adsorbent to communicate between an air introduction hole provided in a converter or a relay and a resin pipe, and that can be used stably over a long period of time. .
The adsorbent is either or both of a desiccant and activated carbon that adsorbs corrosive gas, and the air introduction hole can be provided with a thin pipe or throttle that guides the atmosphere to the adsorbent.

Patent Document 3 discloses a composite sensor capable of detecting a water level and water quality or a flow rate and water quality with a single sensor in a water storage system such as a reservoir or paddy field.
Specifically, a first glass substrate having a pressure inlet for introducing the pressure of the fluid to be measured is disposed on one side of a diaphragm for measuring the differential pressure of the pressure sensor, and the first glass substrate and the spacer 4 are arranged. The 2nd glass substrate which opposes via is arrange | positioned. In the second glass substrate, a pressure introduction port different from the previous pressure introduction hole for introducing the pressure of the fluid to be measured is formed at a position facing the pressure introduction port, and the surfaces of the first and second glass substrates facing each other. Each sensor has a conductive film, and between these conductive films, the conductivity and dielectric constant indicating the water quality of the fluid to be measured can be measured, and a composite sensor that can measure differential pressure (flow rate) and water quality with a single sensor It is.

Further, Patent Document 4 discloses a level difference type water level meter that is provided with a pipe for introducing atmospheric pressure in a liquid-tight manner on the low-pressure side when the differential pressure gauge is used in water, and is hardly affected by the ambient temperature. .
More specifically, a differential pressure detection unit that houses an internal pressure sensor via a high-pressure side diaphragm and a low-pressure side diaphragm and has a liquid-tight space facing the low-pressure side diaphragm, and a pipe connected to the liquid-tight space, When the differential pressure detection unit is installed in water, the water level gauge is configured to extend the pipe to the surface of the water so that the inside of the liquid-tight space is at atmospheric pressure, thereby introducing atmospheric pressure.

  Patent Document 5 discloses an inexpensive and maintainable water level meter that can measure a continuous change in the water level even in an easily contaminated environment such as a paddy field. The water level meter has an opening at the bottom and an upper end. Is a cylindrical container that closes the water level and pressure conversion container (hereinafter referred to as “conversion container”) that converts the water level into air pressure, and is installed above the conversion container. It has pressure measuring means for measuring the pressure as a differential pressure from the atmospheric pressure, and a water level calculating means for calculating the water level from the differential pressure measured by the pressure measuring means, and the water level is confined in the conversion vessel. Since the water level is measured by converting it into static air pressure, the water level gauge does not allow the pressure measuring means to come into direct contact with water or mud.

  Further, in Patent Document 6, by using two sensors, a pressure sensor for water pressure measurement and an atmospheric pressure sensor, a general-purpose electric wire having a simple configuration and a thin resin tube on the outside of the general-purpose electric wire are covered. An injection pressure type water level meter is disclosed that can use a simple cable, is excellent in workability, is superior in cost, and can accurately measure a predetermined water level.

  The disclosed water level meter includes a water level meter body that is connected to one end of the cable and can be thrown into the water, and is provided at the bottom of the water level meter body so that a gas such as air or nitrogen gas is enclosed in a sealed space. A differential pressure measurement unit (water pressure measurement sensor) that measures the differential pressure between the reference pressure and the water pressure by the sealed fluid obtained by sealing in the water, an atmospheric pressure sensor provided separately from the water level meter body, and a differential pressure It is equipped with an output unit that calculates the differential pressure between the differential pressure measured by the measurement unit and the atmospheric pressure detected by the atmospheric pressure sensor, converts the differential pressure into an electrical value, and outputs it. The cable that can be thrown into the cable may be used with a general-purpose wire that is made by coating the outer periphery of the conductor with a resin layer that has corrosion resistance, weather resistance, and electrical insulation. Features that may have been externally fitted A water level meter that.

  Furthermore, Patent Document 7 discloses a hydraulic water level meter that improves measurement accuracy by eliminating an error that cannot be corrected by a conventional water level meter that has been corrected for water density due to a change in water temperature. . The details are as follows: In the water pressure type water level meter that detects the water level by measuring the differential pressure between the water pressure at a predetermined position in the water and the atmospheric pressure, and correcting the water temperature based on the water temperature value, the air column correction based on the altitude value is performed. Measured value with the water column correction circuit and the turbidity sensor, and the turbidity correction circuit that corrects the density change of the water due to the turbidity sensor and the previous water temperature correction. In addition, a water pressure type water level meter added with air column correction based on an altitude value, or a water pressure type water level meter added with air column correction and water density change correction.

  However, each of these various water level gauges and their measuring methods have problems. The water level meter disclosed in Patent Document 1 is a large-scale water level meter introduced by introducing atmospheric pressure to a detector installed under water and a transducer installed on the surface of the water connected by a cable with a hollow pipe. Disclosed an invention that eliminates the pressure fluctuation response delay error and prevents the deterioration of the sensor and electronic circuit, the feature is in the structure of the hollow pipe used for the cable, such a special cable, Production is not easy, it tends to be expensive, and also in terms of maintenance, it is clear that this special cable is structurally difficult to handle, so it is not versatile and requires many water level gauges such as paddy water level measurement. Not suitable for use.

  Furthermore, in the water level meter disclosed in Patent Document 2, a detector installed under water and a converter installed on the water surface or a converter via a relay box are connected by a cable with a hollow pipe. It is a throw-in type water level meter, and it can be used stably over a long period of time by eliminating the measurement error by communicating between the air inlet hole provided in the converter or relay and the resin pipe via the gas adsorbent. In the invention, the feature is that a gas adsorbent is provided between the air introduction hole and the resin pipe, but there is no correspondence regarding the atmospheric pressure fluctuation at the time of measuring the differential pressure due to the size of the air introduction hole. In this respect, it is difficult to accurately measure the behavior of the paddy water level with good responsiveness.

  Further, a water level meter disclosed in Patent Document 3 includes a diaphragm for measuring a differential pressure of a pressure sensor, and a water level provided with a pair of conductive films for measuring conductivity and dielectric constant indicating water quality of a fluid to be measured. Although it is an invention of a composite sensor that can detect water quality or flow rate and water quality with a single sensor, no effective measures have been taken for atmospheric pressure fluctuations during differential pressure measurement due to the size of the air inlet hole In this respect, the same problem as in Patent Document 2 is caused.

  Moreover, in the water level meter and its measurement method disclosed in Patent Document 4, when the differential pressure detection unit having a liquid-tight space is installed in water, the pipe is connected to the water surface so that the inside of the liquid-tight space becomes atmospheric pressure. By extending the pressure, it is possible to introduce atmospheric pressure, but the influence of atmospheric pressure fluctuations in the liquid-tight space caused by the piping that introduces atmospheric pressure into the liquid-tight space cannot be excluded from the measurement data, Problems with accuracy and responsiveness are likely to occur.

  On the other hand, in the water level meter disclosed in Patent Document 5, due to its structure, accurate water level measurement is difficult unless water enters the container, and there is a problem in the effectiveness of measurement data when the water level is low. . Moreover, there exists a problem which is easy to receive to the influence of the temperature change of the air enclosed in the conversion container.

  Moreover, since the water level meter disclosed in Patent Document 6 includes two pressure sensors for measuring water pressure and measuring atmospheric pressure, the water level measurement for controlling the water level of the water stored in the paddy field is provided. If the water levels at many locations must be measured simultaneously, the cost associated with the water level gauge cannot be ignored. Also, the maintainability of the two pressure gauges, the synchronism of the pressure gauges, Has problems in handling such as failure frequency.

  Furthermore, the water level meter disclosed in Patent Document 7 adopts a water level measurement method that adds air column correction based on altitude value and correction of water density change, and is a water pressure type water level gauge with excellent responsiveness and measurement accuracy. However, in the method of measuring a water level by providing a plurality of water level gauges as in an agricultural field, each device by including a device for correcting an air column and correcting a density change of water, like the water level meter of Patent Document 3. There are problems such as increased maintenance complexity, failure frequency, and high water level meter costs.

JP 09-033316 A Japanese Patent Laid-Open No. 08-285660 Japanese Patent Application Laid-Open No. 09-297043 JP 2003-004504 A JP 09-292272 A Japanese Patent Application Laid-Open No. 09-026348 JP-A-11-014429

  In view of the above-described circumstances, the present invention provides a paddy field water level meter that can quickly and accurately measure and control the water level of a paddy field in real time.

  1st invention of this invention is a water level meter for paddy fields which measures the water level of the stored water in a paddy field for controlling the water supply and drainage to the paddy field surrounded by the shore, A water level measurement part, a signal processing part, Consists of a housing that houses the measuring unit, the water level measuring unit comprises a differential pressure measurement pressure sensor that includes a diaphragm having an opening, and a signal cable that transmits the measurement value measured by the sensor to the signal processing unit. A paddle water level meter comprising a hollow housing for storing the sensor in a watertight structure at one end, an air opening provided at the other end of the hollow housing, and a signal processing unit comprising a pressure-water level conversion device and a water level data transfer device It is.

  The second invention of the present invention is a water level meter for paddy fields in which the size of the atmosphere opening in the first invention is larger than the size of the opening of the diaphragm.

  According to a third aspect of the present invention, the water level measuring unit of the water level meter according to the first and second aspects of the present invention includes a temperature sensor, the signal processing unit includes a water temperature detecting device, and the water level is compensated for a change in water pressure due to a change in water temperature. It is a water level meter for paddy fields used for measurement.

  According to a fourth aspect of the present invention, there is provided a water level gauge for paddy fields according to the first to third aspects, wherein the hollow casing of the water level gauge is made of resin and the signal processing unit is installed in the hollow casing.

  A fifth invention of the present invention is a water level meter for paddy fields in which the water level gauge according to the first to fourth inventions is a self-supporting water level meter equipped with a self-supporting member.

  ADVANTAGE OF THE INVENTION According to this invention, it is a paddy field water level meter which is easy to handle as a paddy field water level meter, has excellent responsiveness and data accuracy, and is low in cost. It is possible to realize one-point or multi-point water level measurement of the stored water and control based on the measurement data quickly and accurately in real time, and it has a significant industrial effect that leads to good growth of cultivated crops. It is what you play.

It is an illustration figure which shows an example of the Example of the water level meter used by this invention. It is a schematic cross section showing a schematic structure of a differential pressure measurement pressure sensor. It is an illustration figure which shows the other example of the Example of the water level meter used by this invention. It is an illustration figure which shows the other example of the Example of the water level meter used by this invention. It is an illustration figure which shows the other example of the Example of the water level meter used by this invention. It is an illustration figure which shows the form at the time of the paddy field installation of the water level meter used by this invention. It is an illustration figure which shows the other example of the Example of the water level meter used by this invention. It is an illustration figure which shows the other example of the Example of the water level meter used by this invention. It is an illustration figure which shows the other example of the Example of the water level meter used by this invention. It is an illustration figure which shows the Example of the water level meter provided with the water temperature compensation used by this invention. An example of the installation state of the water level meter for paddy fields concerning the present invention is shown, (a) is a top view and (b) A sectional view in an aa line. It is a figure which shows the characteristic of the installation to the paddy field of the paddy field water level meter which concerns on this invention. It is a figure which shows the characteristic 2 of the installation to the paddy field water level meter which concerns on this invention, (a) is a stand-type self-supporting water level meter, (b) is the schematic of a socket-type self-supporting water level meter.

With reference to FIGS. 1-13, the water level meter for paddy fields of this invention is demonstrated below.
In the measurement of the water level of the paddy field, a water level meter that measures the water level of the stored water stretched on the paddy field accurately is indispensable, and the outline of the water level meter according to the present invention will be described.

[Water level gauge]
1 and 2 show an outline of a water level gauge for paddy fields according to the present invention, and FIGS. 3 to 7 show other embodiments.

1 and 3 to 10 are schematic diagrams of a water level meter, FIG. 2 is a schematic structural diagram showing a schematic structure of a differential pressure measuring pressure sensor used in the water level meter, 10, 10 a to 10 h are water level meters for paddy fields, 1 is a differential pressure measuring pressure sensor, 1a is a sensor housing, 1b is a sensor atmospheric pressure port, 1c is a sealing liquid, 1d is a sensor water pressure port, 2 is a diaphragm, 2a is a diaphragm opening, 3 is a hollow housing portion, 3a Is an air outlet, 3b is a signal cable outlet, 4 is a signal cable, 5 is a filter, 6 is a temperature sensor, 30 is an air outlet (integrated type), 100 is a pressure-water level conversion device, and 101 is water level data. transfer device, 102 temperature sensing unit, phi _a is air opening size, phi _D is the size of the diaphragm aperture, phi ₁ the sensor pressure port size, SC is the sensor element, the black arrows atmospheric pressure, Open arrows indicate water pressure It is be one.
The air opening 3a is directed to the ground as shown in FIG. Or, as shown in FIG. 3, it is installed in one of the horizontal directions horizontal to the ground. On the other hand, the signal cable outlet 3b is directed to the ground as shown in FIGS. 1 and 3, or in either the horizontal direction horizontal to the ground as shown in FIG. 4 or the zenith direction as shown in FIG. install. Moreover, since the paddy soil has water permeability as shown in FIG. 6, even if the sensor portion is slightly embedded in the ground surface, the groundwater level is transmitted as water pressure, so there is no problem.

FIG. 2 is a schematic diagram of the structure of the water level meter for paddy fields used in the present invention, and shows the schematic structure of the water level meter for paddy field 10 shown in FIG. 1 and the differential pressure measuring pressure sensor 1 used in the water level gauge. Will be described below.
The water level meter according to the present invention includes a water level measurement unit including at least a differential pressure measurement pressure sensor for measuring a differential pressure between the water pressure and the atmospheric pressure, and the measurement data obtained by the sensor as “pressure-water level conversion device”, “water level data” It consists of a signal processing unit that transmits to the outside via a “transfer device” and a hollow housing that houses the water level measuring unit in a watertight structure.

  The paddy field water level gauge 10 includes a diaphragm (see also FIG. 2 and reference numeral 2) having an opening (see FIG. 2 and reference numeral 2a) having a size equal to or larger than the size of the sensor water pressure port. The differential pressure measurement pressure sensor 1 capable of measuring the pressure difference from the measured object (reserved water) (water pressure), and the sensor 1 is housed in a watertight structure at one end (A side) and at the other end (B side). A hollow housing part 3 provided with an air opening 3a and a signal cable outlet 3b for pulling out a signal cable 4 for transmitting a measurement signal from the sensor 1, and obstacles such as water, moisture, mud, animals and plants in the water level gauge It comprises a filter 5 that prevents intrusion of objects.

Further, as major features, the size φ _A of the atmosphere opening 3 a and the size φ _D (see FIG. 2) of the diaphragm opening 2 a of the pressure sensor 1 are φ _A / φ _D ≧ 1. It has a relationship of zero.

2 is a schematic cross-sectional view of the schematic structure of the differential pressure measurement pressure sensor 1. 1 is a differential pressure measurement pressure sensor, 1a is a sensor housing, 1b is a sensor atmospheric pressure port, 1c is silicon oil, fluorine oil, or the like. Filled liquid, 1d is a sensor water pressure port, 2 is a diaphragm, 2a is a diaphragm opening, and indicates the effective contact range of the diaphragm surface on the side in contact with the object to be measured (reserved water). Also in the diaphragm opening 2a, a sealing liquid may be used to protect the sensor. SC is the sensor element, phi _D represents a measure of the previous contact effective range by the size of the diaphragm aperture, if the shape of the diaphragm aperture is circular or symmetrical (figure having an axis of symmetry), the diameter, symmetrical This is indicated by the axial length or area. In the case of an asymmetrical shape, the area is assigned. The scale of “size” is also applied to the size of the atmosphere opening 3a, the size of the hollow casing 3, and the size of the sensor water pressure port 1d.

The paddy field level gauges 10, 10a to 10h having the structure shown in FIG. 1 and FIG. 3 to FIG. 10 have an air opening 3a or 30 and the size φ _A of the air opening is measured by a differential pressure measuring pressure sensor. 1, the relationship of φ _A / φ _D ≧ 1.0 with respect to the size φ _D of the opening 2a of the diaphragm 2 for introducing the water pressure, that is, the size of the atmosphere opening 3a is the opening 2a of the diaphragm 2 If the opening is larger than the size of, the response of atmospheric pressure will be further enhanced, and the synchronization between the water pressure measurement and the atmospheric pressure measurement can be enhanced during the differential pressure measurement to determine the paddy water level. As a result, the effect of reducing the error of the differential pressure measurement is brought about. It also has the function of improving the accuracy of real-time measurement.

The relation “φ _A / φ _D ≧ 1.0” means that the size of the air opening 3a is equal to or larger than the size of the opening 2a of the diaphragm 2, and when this value is smaller than 1.0, Although the transmission force of the atmospheric pressure fluctuation to diaphragm 2, that is, the responsiveness is lowered, the water level for paddy field is effective for disturbance factors such as strong wind, heavy rain, and clogging of garbage at the opening. It is recommended to select a water level gauge with an appropriate opening depending on the environment where the gauge is installed. The upper limit is preferably the following, based on the ratio between the size of the hollow casing 3 and the size of the diaphragm opening 2a.

Here, when the water level rises or falls by variously changing the relationship of “φ _A / φ _D ”, as a result of investigating the time required for the water level gauge to show the phenomenon, that is, the response time, When the water level is raised by 10 cm, the influence on the response time of the “φ _A / φ _D ” relationship when the water level is lowered has the results shown in Table 1. Note that the test conditions were changed by changing only the size of the air opening.

Further, the size φ _A of the atmospheric pressure opening 3 a may have a relationship of “φ _A / φ ₁ ≧ 1.0” with the size φ ₁ of the sensor water pressure port 1 d of the differential pressure measuring pressure sensor 1. This contributes to the accuracy of differential pressure measurement.

Moreover, it is useful also for prevention of the dew condensation which the temperature difference resulting from the relationship of the arrangement position of the air release port 3a and the pressure sensor 1 produces. Furthermore, since the influence of the pressure leaking from the inside of the apparatus 100 or 101 via the signal cable 4 can be eliminated, accurate measurement can be performed.
As described above, the paddy field level meter according to the present invention is a result of considering the paddy field-specific mud, plant group, paddy field water level, etc. It is a water level meter that can be installed and removed as well as the accuracy of measuring the water level in paddy fields. Hereinafter, details of the paddy water level gauge will be further described with reference to the drawings.

Another embodiment of the water level gauge for paddy fields used in the present invention indicated by reference numerals 10a to 10h in FIGS. 3 to 10 will be described below.
3-5 has shown the example from which the arrangement | positioning of the atmospheric | air release port 3a and the signal cable outlet 3b differs from the water level gauge 10 shown in FIG.
The water level gauge 10a in FIG. 3 is different from the water level gauge 10 in FIG. 1 in the direction of the atmosphere opening 3a, and the atmosphere opening is opened in the horizontal direction.
In the water level gauge 10b of FIG. 4, the cable opening 3b is open in the horizontal direction.
In the water level gauge 10c of FIG. 5, the cable opening 3b is opened in the direction directly above the sensor 1a.

  A water level meter 10d for paddy fields shown in FIG. 6 is an illustrative view showing a form when the paddy field is arranged in the water level gauge shown in FIG. 1. In order to bury the tip of the water level meter under the paddy field, 9 and a self-supporting support 8 in the shape of a disk or a disk that plays the role of floating so that the water level gauge stands on the paddy field, and the water level gauge does not sink from the paddy surface, and a water measuring port 7a is provided on the upper part of the fist 9 It has a form. Although the sensor 1 is slightly buried in the ground, since the paddy soil has water permeability, even if the sensor 1 is slightly buried in the ground from the ground surface, the groundwater level is transmitted as water pressure. It is not a problem for water level measurement.

FIG. 7 is an illustrative view showing a water level meter 10e for paddy fields provided with an integrated atmosphere opening 30 in which both the atmosphere opening and the signal cable outlet are integrated.
The integrated air opening 30 of this type aims at both taking out the signal cable and improving the responsiveness of atmospheric pressure, and preventing foreign matter such as water, mud, animals and plants from entering the water level gauge (inside the hollow casing). The filter 5a is provided, and it is desirable that the filter 5a is further breathable.

  FIG. 8 shows a data transfer device 101 that wirelessly transfers measurement data to the outside by using a resin-made hollow casing 3 in a water level gauge of the same type as the paddy field water gauge of FIG. The paddy field water level meter 10f arranged inside the section 3 includes the "pressure-water level conversion device 101" and has an advantage that a more compact water level meter can be obtained.

FIG. 9 shows a water level gauge 10g for paddy fields used by replacing the hollow casing portion 3 with a hollow flexible tube or a bellows tube and using it as an inverted S-shape as shown in FIG.
Thus, when a hollow flexible tube or a bellows tube is used, there is an advantage that a self-standing water level meter can be obtained without preparing a separate self-standing jig.

FIG. 10 shows a paddy field in which a water temperature detection temperature sensor 6 for compensating for a water pressure fluctuation due to the water temperature at the time of differential pressure measurement is provided in the proximity of the differential pressure measurement pressure sensor 1 in the paddy field water level meter 10 of FIG. It is an illustration figure which shows the water level meter 10h.
The temperature data measured by the temperature sensor 6 installed close to the differential pressure measurement pressure sensor 1 is sent to the water temperature detection device 102 and transmitted from the water level data transfer device 101 to the outside.

  In the differential pressure measurement pressure sensor 1 used in this type of paddy field water level gauge 10h, when the sensor housing 1a is made of a material having good thermal conductivity, the water temperature is transmitted to the temperature sensor 6 in the water level gauge. It is possible to play a role and improve the responsiveness of temperature measurement. The material is preferably a metal, and aluminum or stainless steel is desirable in consideration of durability. In addition, since the temperature and the water temperature of the sensor casing become substantially constant when time elapses, this temperature sensor has an advantage that the water temperature can be measured through the sensor casing. In this method, there is a time difference in the constant temperature, but there is no problem even if the sensor housing is made of resin.

Next, the example of the usage method of the paddy field water level meter which concerns on this invention is shown below.
FIG. 11 shows an example of the installation state of the paddy field water level meter according to the present invention, in which (a) is a plan view and (b) a sectional view taken along the line aa.
A water supply facility 20 for supplying water from the main waterway 25 into the field 23, and a waterside 22 having a drainage facility 21 having a water outlet 21a for discharging the water supplied from the water supply facility to the outside of the waterway 26 and the like from the field. The paddy field level gauge 10 that measures the water level of the paddy field is required for the power supply position P1 from the water supply / drainage facility that operates electrically, the vicinity P2 of the shore 22 and the P3 in the field. The water level is measured sequentially by arranging one or more at the position, and used as control data for the water level behavior in the field.
In addition, an appropriate number of water level gauges are installed along the water flow path (black arrow) that appears during the supply and discharge of stored water in the field, and the water level of the stored water in the field is measured. In that case, as a paddy field water level meter installed in the field, a self-standing water level meter that can be easily installed and removed can be used other than permanent installation.

FIG. 12 is a diagram showing individual installation methods for the paddy field water level gauge according to the present invention. In FIG. 12, 10 is a water level meter for paddy fields, 1 is a differential pressure measuring pressure sensor, 2 is a diaphragm, 3a is an air opening, black arrows are atmospheric pressure, and white arrows are water pressures.
As shown in FIG. 12, the paddy field level gauge 10 has an air opening 3a at a position h [m] higher than the top of the bank of the irrigation channel along the shore that surrounds the paddy field or the paddy field that supplies and drains the paddy field It is installed at an installation height h).
The installation height h is provided so that the air opening 3a is located above the ridge or the top of the irrigation canal, so that the influence of the entanglement wind by the shore or the irrigation canal wall can be eliminated, and the atmospheric pressure and its variation can be responsive. It is possible to communicate well and accurately.

The diaphragm is displaced by the differential pressure between the transmitted atmospheric pressure and the water pressure obtained from the water level of the paddy field where the diaphragm 2 of the differential pressure measuring pressure sensor 1 is sensed by the diaphragm opening 2a, and the sensor element SC on the diaphragm 2 is displaced. The differential pressure signal is sent to the pressure-water level conversion device 100 to become water level data, and the obtained water level data is sent to the water level data transfer device 101 and transmitted externally.
Therefore, the installation height h has a great influence on measuring the differential pressure with high responsiveness and accuracy together with the size of the air opening.

  The range of the height h is preferably 0 to 10 cm, considering that the unevenness of the surface is about ± 5 cm, and if it is less than the lower limit, it is easily affected by the shore and the irrigation canal, and is responsive and accurate. When the value exceeds the upper limit, it is undesirably affected by the wind blowing through the field and causes problems in responsiveness and accuracy.

Further, the water level gauge pressure sensor side has an open air opening 3a at a position where the installation height h is satisfied when paddy water is stored, or when there is no stored water. To be provided.
In order to prevent intrusion of obstacles such as mud and algae, an air permeable filter may be provided inside the air opening 3a.

In the paddy field water level measurement method, the paddy field water level meter according to the present invention has a feature that it can be installed at any time in a paddy field by using a self-supporting jig.
FIG. 13 shows the form of the self-supporting water level gauge. (A) is the schematic which shows the example of a stand type self-standing water level meter, (b) is the schematic which shows the example of a socket type self-standing water level meter. In FIG. 13, 7A is a stand-type self-supporting jig, 7B is a socket-type self-supporting jig, 7a is a water measuring port, 7b is a support rod, 7c is a water level gauge gripping arm, and 8 is a self-supporting support for self-supporting the water level gauge. The tool 9 is used to make it easy to embed a water level gauge on the surface. In the self-standing water level meter, a battery using a power source or a self-powered power source such as a solar cell is easy to handle and a water level meter network can be easily formed.

How to use is to bury the buried part in the paddy field and fix it, but determine the installation location in advance, install the self-supporting jigs 7A and 7B at that location, and install the water level meter at the required location. May be.
The predetermined installation location is selected by checking the change in the water flow path due to the inclination or unevenness of the ground surface of the paddy field when the water is drained into the paddy field.

DESCRIPTION OF SYMBOLS 1 Differential pressure measurement pressure sensor 1a Sensor housing 1b Sensor atmospheric pressure port 1c Filled liquid 1d Sensor water pressure port 2 Diaphragm 2a Diaphragm opening part 3 Hollow housing part 3a Atmospheric release port 3b Signal cable outlet 4 Signal cable 5, 5a Filter 6 Temperature sensor 7A Stand-type self-supporting jig 7B Socket-type self-supporting jig 7a Water measuring port 7b Support rod 7c Water level gauge gripping arm 8 Self-supporting tool 9 Yajiri 10, 10a to 10h Paddy water level gauge 20 Water supply equipment 21 Drainage equipment 21a Falling water Mouth 22 shore 23 farmland (paddy field)
24 Cultivated crop (rice)
25 Main line 26 Canal 30 Open to the atmosphere (integrated)
100 pressure-water level conversion device 101 water level data transfer device 102 water temperature detection device φ _A size of air opening φ _D size of diaphragm opening φ ₁ size of sensor water pressure port SC sensor element h (inside of air opening port Installation height from P1 Paddy field water level gauge installation location (water supply / drainage facility power supply range)
P2 Paddy field water level gauge installation location (on the shore, near the canal)
P3 Paddy field water level gauge installation location (in the field)

Claims (5)

A water level meter for paddy fields,
Consists of a water level measurement unit, a signal processing unit, and a housing that houses the measurement unit,
The water level measurement unit comprises a differential pressure measurement pressure sensor including a diaphragm having an opening, and a signal cable that transmits a measurement value measured by the sensor to a signal processing unit,
The housing is a hollow housing that houses the sensor in a watertight structure at one end, and has an air opening on the other end side of the hollow housing,
The water level meter for paddy fields in which the signal processing unit includes a pressure-water level conversion device and a water level data transfer device.   The water level meter for paddy fields according to claim 1, wherein the size of the atmosphere opening is equal to or larger than the size of the opening of the diaphragm. The water level measurement unit of the water level meter includes a temperature sensor, the signal processing unit includes a water temperature detection device,
The water level meter for paddy fields according to claim 1 or 2, which is used for measuring a water level compensated for a change in water pressure due to a change in water temperature.   The water level meter for paddy fields according to any one of claims 1 to 3, wherein the hollow casing of the water level gauge is made of resin, and the signal processing unit is installed in the hollow casing.   The water level meter for paddy fields according to any one of claims 1 to 4, wherein the water level meter is a self-supporting water level meter equipped with a self-supporting member.

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