Water level gauge, water level gauge storage component, and water level gauge installation structure

Abstract

To provide a water gauge that has a stain-proof sensor part, and can measure a water level of a field accurately and stably.SOLUTION: A water gauge 50 has a sensor body 52 having a sensor part 60, a vertical cylindrical sensor case 70 having a vent hole 70a and a first flow hole, and a shut film 72 that is formed in an expandable bag with an opening, so that its inside is in communication with the first flow hole. The shut film has clear water to be stored inside, with its outer surface to be in contact with field water.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a water level gauge, a water level gauge storage member, and a water level gauge installation structure, and more particularly to a water level gauge, a water level gauge storage member, and a water level gauge installation structure for detecting the water level in a farm field, for example. [Background technology]

[0002] An example of this type of conventional water level meter is disclosed in Patent Document 1. In the technology of Patent Document 1, a single pipe (rod-shaped fixture) is inserted into the field, and a housing of the water level meter (sensor terminal) is connected and fixed to the single pipe using a universal clamp or the like, thereby erecting the water level meter in the field. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-103099 Summary of the Invention [Problem to be solved by the invention]

[0004] Field water contains many impurities such as mud, straw, and fallen leaves. In the technology of Patent Document 1, the field water is brought into direct contact with the sensor part of the water level meter, which can lead to measurement errors due to impurities adhering to the sensor part. In addition, the sensor part is easily soiled, so frequent maintenance is required, and this maintenance is also time-consuming.

[0005] Therefore, a primary object of the present invention is to provide a novel water level gauge, a water level gauge storage member, and a water level gauge installation structure.

[0006] Another object of the present invention is to provide a water level gauge, a water level gauge storage member, and a water level gauge installation structure that are resistant to contamination of the sensor portion and that can accurately and stably measure the water level in a farm field. [Means for solving the problem]

[0007] The first invention is a water level meter that detects the water level in a field, and includes a sensor body having a sensor unit that detects the water level, a vertical cylindrical sensor case that has an air vent formed at the top and a first water inlet formed at the bottom and that houses the sensor unit, and a sealing membrane that is formed in the shape of an expandable bag with an opening and is arranged so that its interior communicates with the first water inlet, and fresh water is stored inside the sealing membrane, and the sealing membrane is arranged so that its outer surface comes into contact with the field water.

[0008] In a first aspect of the present invention, the water level meter comprises a sensor body having a sensor unit, a vertically cylindrical sensor case that houses the sensor unit, and a sealing membrane formed in the shape of an expandable bag. An air vent is formed in the upper part of the sensor case, and a first water passage port is formed in the lower part. The sealing membrane has an opening, and is provided so that its interior communicates with the first water passage port of the sensor case. Furthermore, the sealing membrane is provided so that fresh water is stored inside and its outer surface comes into contact with field water.

[0009] In this type of water level meter, the sealing membrane expands and contracts in response to fluctuations in the water level in the field, causing the clear water level to fluctuate up and down, and the sealing membrane stops expanding and contracting when the internal and external pressures acting on the sealing membrane are balanced, that is, when the clear water level and the water level in the field are equal.In other words, the state in which the clear water level and the water level in the field are equal is maintained, so the water level in the field can be detected by detecting the clear water level with the sensor unit.

[0010] According to the first invention, a blocking membrane with fresh water stored inside is used, and the fresh water, rather than field water, is brought into contact with the sensor unit to detect the water level in the field. Therefore, the sensor unit is less likely to become dirty, and the water level in the field can be measured accurately and stably. Furthermore, because the sensor unit is less likely to become dirty, the frequency of maintenance of the water level meter can be significantly reduced.

[0011] A second invention is according to the first invention, and the opening of the shielding film is connected to the sensor case in a watertight manner.

[0012] The third invention is dependent on the first or second invention, and the air vent is formed at a position above the upper measurement limit position of the sensor unit, and the first water passage is formed at a position below the lower measurement limit position of the sensor unit.

[0013] The fourth invention is dependent on the first or second invention, and has a second water passage opening that opens at a position lower than the lower measurement limit position of the sensor unit, and is provided with a bottomed tubular protective member that is arranged to surround the blocking membrane.

[0014] According to the fourth aspect of the present invention, the protection member surrounding the shielding film is provided, so that the shielding film is appropriately protected and can be appropriately operated (expanded / contracted).

[0015] A fifth invention is dependent on the fourth invention, and the protective member is provided so as to surround the entire shielding film.

[0016] A sixth invention is according to the fifth invention, and the protection member has an air vent formed in an upper portion thereof.

[0017] According to the sixth aspect of the present invention, the air inside the protective member can be appropriately supplied and exhausted.

[0018] A seventh invention is according to the fourth invention, and the protection member has a bottom-raised portion provided at a lower portion of the side wall, and a mud drain port formed in the bottom wall.

[0019] According to the seventh aspect of the present invention, even if mud gets into the protective member, it is discharged below the bottom wall through the mud drainage port, thereby preventing the accumulated mud from adversely affecting the operation of the shielding membrane.

[0020] An eighth invention is according to the first or second invention, and the opening of the shielding film is connected to a lower end of the sensor case.

[0021] According to the eighth aspect of the present invention, the size of the shielding film (and the protective member) can be reduced to the minimum necessary.

[0022] A ninth invention is according to the eighth invention, and the lower end of the sensor case is formed in a tapered shape that increases in diameter downward.

[0023] According to the ninth aspect of the present invention, when the water level inside the shielding membrane rises, fresh water flows smoothly into the sensor case.

[0024] A tenth invention is according to the fourth invention, and a lower end of the shielding film is connected to a bottom wall of the protection member.

[0025] According to the tenth aspect of the present invention, the lower end of the shielding film is prevented from deforming to float off the bottom wall, making it difficult for mud to accumulate between the lower end of the shielding film and the bottom wall, and also preventing air from becoming trapped. Therefore, it is possible to prevent the accumulated mud and trapped air from adversely affecting the operation of the shielding film.

[0026] An eleventh invention is according to the fifth invention, wherein the protective member has a horizontal pipe portion that protrudes laterally, and the second water passage port is formed at a tip end of the horizontal pipe portion.

[0027] According to the 11th invention, field water can be drawn from a position away from the sensor body (and therefore the water tap), that is, a stable water level can be detected at a position that is less affected by water level fluctuations during water supply, thereby further improving the detection accuracy of the water level meter.

[0028] A twelfth invention is according to the first or second invention, wherein the sensor case has a horizontally tubular extending portion at a lower portion thereof, and the first water passage port is formed at a tip end of the extending portion.

[0029] According to the 12th invention, field water is drawn from a position away from the sensor body (and therefore the water tap), that is, a stable water level is detected at a position that is less affected by water level fluctuations during water supply, thereby further improving the detection accuracy of the water level meter.

[0030] A thirteenth invention is according to the first or second invention, and the sensor main body is provided detachably with respect to the sensor case.

[0031] According to the thirteenth aspect of the present invention, flexible operation is possible, such as removing only the sensor body from the field and storing it in a storehouse during agricultural off-seasons such as winter.

[0032] A fourteenth invention is according to the first or second invention, and the sensor main body includes an inner cover that protects the sensor portion.

[0033] According to the fourteenth aspect of the present invention, the sensor section can be protected more appropriately.

[0034] A fifteenth invention is according to the first or second invention, wherein the amount of fresh water is greater than the volume of space in the sensor case below an upper measurement limit position of the sensor unit.

[0035] A sixteenth invention is dependent on the second invention, and the shielding film is provided to cover the lower part of the sensor case, and the sensor case has a second ventilation hole formed directly below the connection position with the shielding film.

[0036] According to the sixteenth aspect of the present invention, the air inside the shielding film can be kept at an appropriate atmospheric pressure.

[0037] A seventeenth invention is dependent on the second invention and includes a second shielding membrane formed in an expandable and contractible bag shape and airtightly connected to the ventilation hole, and a second protective member having a third ventilation hole and arranged to surround the second shielding membrane.

[0038] According to the seventeenth aspect of the present invention, the air inside the sensor case and the shielding membrane is not discharged to the outside, so that the fresh water is prevented from decreasing due to evaporation (decrease in the amount of fresh water), and it is not necessary to replenish the fresh water.

[0039] An eighteenth invention is according to the fourth invention, and the protective member restricts the shape of the shielding film to a certain shape when expanded.

[0040] A nineteenth invention is according to the first or second invention, wherein the sensor section is formed in a rectangular plate shape, and the sensor case is formed in a rectangular tube shape that fits along the outer surface of the sensor section with a predetermined gap therebetween.

[0041] A twentieth invention is according to the first or second invention, and the sensor unit is a pressure-type sensor and is housed in the lower end of the sensor case.

[0042] The 21st invention is a water level gauge storage member that constitutes a water level gauge that detects the water level in a field together with a sensor main body having a sensor unit, and is equipped with a vertical cylindrical sensor case that has an air vent formed at the top and a first water inlet formed at the bottom and that houses the sensor unit, and a sealing membrane that is formed in the shape of an expandable bag with an opening and is arranged so that its inside is connected to the first water inlet.

[0043] In a 21st aspect of the invention, a water level gauge housing member is used together with a sensor body having a sensor unit to form a water level gauge that detects the water level in a farm field. This water level gauge housing member comprises a vertically tubular sensor case that houses the sensor unit, and a sealing membrane formed in the shape of an expandable and contractible bag. An air vent is formed in the upper part of the sensor case, and a first water passage is formed in the lower part. The sealing membrane has an opening, and is arranged so that its interior communicates with the first water passage of the sensor case.

[0044] According to the 21st invention, it is possible to configure a water level meter that can accurately and stably measure the water level in a farm field by making it possible to prevent the sensor part of the sensor main body from becoming dirty. Furthermore, it is possible to configure a water level meter that can significantly reduce the frequency of maintenance, and it is also possible to detach and store only the sensor main body when not in use.

[0045] The 22nd invention is an installation structure for a water level meter that detects the water level in a farm field, comprising a water level meter according to any one of the first to eighteenth inventions, and a cylindrical or bottomed cylindrical manhole that has a plurality of holes penetrating in the thickness direction and is installed in the farm field to surround the water level meter.

[0046] According to the 22nd invention, as with the first invention, the sensor unit can be made less susceptible to contamination, allowing for accurate and stable measurement of the water level in the field. Furthermore, because the sensor unit is less susceptible to contamination, the frequency of maintenance of the water level meter can be significantly reduced. Furthermore, since the water level meter is installed in a manhole, the water level meter itself is properly protected, and the manhole prevents large debris and mud from entering the area around the water level meter, making it even more difficult for the sensor unit to become dirty. [Effects of the Invention]

[0047] According to this invention, the sensor unit can be made less susceptible to contamination, enabling accurate and stable measurement of the water level in the field. Furthermore, because the sensor unit is less susceptible to contamination, the frequency of maintenance of the water level meter can be significantly reduced.

[0048] The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments, which proceeds with reference to the accompanying drawings. [Brief explanation of the drawings]

[0049] [Figure 1] 1 is a diagram showing a field water management system equipped with a water level meter according to an embodiment of the present invention; [Figure 2] FIG. 2 is a cross-sectional view showing the internal structure of the electric actuator. [Figure 3] FIG. [Figure 4] A cross-sectional view showing the internal structure of the water level gauge [Figure 5] FIG. [Figure 6] FIG. [Figure 7] FIG. 3 is a cross-sectional view showing a water level gauge housing member. [Figure 8] FIG. 2 is an illustrative view for explaining the operation of the water level meter. [Figure 9] FIG. 2 is an illustrative view for explaining the operation of the water level meter. [Figure 10] FIG. 2 is an illustrative view for explaining the operation of the water level meter. [Figure 11]FIG. 10 is a schematic diagram showing a water level meter according to another embodiment of the present invention. [Figure 12] FIG. 10 is a schematic diagram showing a water level meter according to still another embodiment of the present invention. [Figure 13] FIG. 10 is a schematic diagram showing a water level meter according to still another embodiment of the present invention. [Figure 14] FIG. 10 is a schematic diagram showing a water level meter according to still another embodiment of the present invention. [Figure 15] FIG. 10 is a schematic diagram showing a water level meter according to still another embodiment of the present invention. [Figure 16] FIG. 10 is a schematic diagram showing a water level meter according to still another embodiment of the present invention. [Figure 17] FIG. 17 is an illustrative view schematically showing a cross section of the water level meter of FIG. 16. [Figure 18] FIG. 10 is a schematic diagram showing a water level meter according to still another embodiment of the present invention. [Figure 19] FIG. 19 is an illustrative view schematically showing a cross section of the water level meter of FIG. 18. DETAILED DESCRIPTION OF THE INVENTION

[0050] 1, a water level meter 50 according to one embodiment of the present invention is used in a field water management system 10 (hereinafter simply referred to as "system 10") to detect the water level of a field 100. As will be described in detail later, the water level meter 50 comprises a sensor body 52 and a water level meter housing member 54, and is installed in a manhole 56 provided for the water level meter 50.

[0051] First, before specifically describing the water level meter 50, we will briefly describe an example of the configuration of the system 10. However, the configuration of the system 10 (specific configurations of the water tap 12, the water outlet 14, and the electric actuator 16, etc.) is not limited to this example and can be modified as appropriate.

[0052] As shown in Fig. 1, system 10 is a farm facility that manages water in a farm field 100 by remote control or automatic control based on a pre-stored program. In this embodiment, system 10 includes a water inlet 12 and a water outlet 14, and electric actuators 16 are attached to each of water inlet 12 and water outlet 14. In other words, electric actuators 16 having the same structure are used to drive the displacement mechanisms of water inlet 12 and water outlet 14.

[0053] In this embodiment, the system 10 includes multiple cultivated areas separated by ridges 102. A water tap 12 and a water outlet 14 are installed in each cultivated area, and each electric actuator 16 attached to each tap 12 and outlet 14 is wirelessly connected to a repeater (parent device) using a wireless communication method conforming to a specified low-power wireless standard (920 MHz band). Each electric actuator 16 is then wirelessly connected to a remote control terminal such as a user's smartphone, tablet, PDA, or PC via the repeater and a management server or the like installed on the network. However, the electric actuator 16 may also wirelessly communicate with an external device such as the management server or remote control terminal without using a repeater.

[0054] It is preferable to use cloud computing for this wireless communication. For example, information acquired by each electric actuator 16 (information on the status of the water faucet 12 and the water outlet 14, such as the valve opening degree of the water faucet 12 and the outlet height of the water outlet 14, and sensor information such as the water level in the field 100 received from the water level gauge 50) is constantly transmitted to and stored in a cloud server, which is an example of a management server. A user can access the cloud server from a remote control terminal to check the information acquired by each electric actuator 16 and remotely control each electric actuator 16 using the remote control terminal to manage the water in the field 100.

[0055] The water hydrant 12 is a water supply device for controlling the water supply from an irrigation pipeline 106 to a cultivated area (field 100), and has a displacement mechanism including a valve stem, a valve element, etc. In this embodiment, a water hydrant 12 of the type that is widely used, in which the valve stem and valve element move up and down as the valve stem rotates, is used. This type of water hydrant 12 is placed in a water supply pit 104 provided on a levee 102, and is attached to the downstream end of a branch pipe 108 that branches off from a water pipeline 106 laid under the levee 102 and extends into the field 100. An electric actuator 16 is attached to the water hydrant 12, and the displacement mechanism (valve stem and valve element) of the water hydrant 12 is operated by the electric actuator 16.

[0056] On the other hand, the water outlet 14 is a drainage device for controlling drainage from the field 100 and has a displacement mechanism including a partition. In this embodiment, a water outlet 14 with a water level setting function is used. Briefly, the water outlet 14 has a cylindrical partition 18 whose upper opening functions as a drainage outlet. The partition 18 moves up and down to adjust the height of the drainage outlet. The water outlet 14 is disposed in a drainage basin 110 provided on the levee 102 and attached to the upstream end of a drainage pipe 114 extending to a drainage channel 112. An electric actuator 16 is attached to the water outlet 14, and the displacement mechanism (partition) of the water outlet 14 is moved up and down by the electric actuator 16. When attaching the electric actuator 16 to the water outlet 14, an adapter 20 is used, which converts the rotational force of the electric actuator's rotation shaft 46 (see FIG. 2 ) into a vertical (axial) force and transmits it to the partition.

[0057] 2 together with Fig. 1, the electric actuator 16 includes a cylindrical main body case 30. A solar cell panel 32 is detachably attached to the top of the main body case 30. The solar cell panel 32 is supported at a predetermined angle by a bent plate-shaped metal holder 34.

[0058] The main body case 30 also accommodates an electronic board 36, a storage battery 38, and a drive mechanism including a motor 40, a main gear 42, and the like.

[0059] Although not shown, the electronic board 36 is provided with a control unit including a CPU and memory, and a wireless communication unit including a wireless communication module. The motor 40, operation panel 48, wireless communication unit, water level indicator 50, and other components are electrically connected to the control unit. The CPU of the control unit is responsible for overall control of the electric actuator 16 and controls the driving of the motor 40 and other components. Memory is a comprehensive term that refers to ROM, RAM, HDD, and other components, and stores control programs that control the operation of the electric actuator 16 and functions as a work area when the CPU is operating. The wireless communication unit is also connected to an antenna (not shown), and performs wireless communication with external devices such as repeaters via this antenna.

[0060] The storage battery 38 stores the power generated by the solar panel 32. The motor 40 is driven by the power stored in the storage battery 38. A small gear 44 is provided at the tip of the output shaft 40a of the motor 40, and the main gear 42 is connected to the small gear 44, so that it receives driving force from the motor 40 and rotates around its axis.

[0061] The main gear 42 is a double-boss type gear, and a substantially cylindrical rotating shaft 46 is inserted into the shaft portion of the main gear 42. A coupling portion 46a is formed at the lower end of this rotating shaft 46, which is connected to the valve shaft of the faucet 12. A key groove 42a extending along the axial direction is formed on the inner peripheral surface of the shaft portion of the main gear 42, and a sliding key 46b which fits into the key groove 42a is formed on the outer peripheral surface of the rotating shaft 46 so as to extend along the axial direction. As a result, the rotating shaft 46 rotates as the main gear 42 rotates, and is able to slide axially relative to the shaft portion of the main gear 42.

[0062] An operation panel 48 for manually (electrically operated) operating the motor 40 is provided on the outer surface of the main body case 30. The operation panel 48 is appropriately provided with a main power switch, an up button, a down button, a selection button for switching the operation mode of the electric actuator 16 (remote mode, automatic mode, manual mode, etc.), etc. The operation panel 48 is also provided with a connection terminal for connecting a wire 58 extending from the water level gauge 50, etc.

[0063] In a water faucet 12 equipped with the electric actuator 16 described above, for example, a user accesses a management server using a remote control terminal and sends an operation instruction (control signal) to fully close, fully open, or open the water faucet 12 to an arbitrary degree, and a control signal corresponding to this operation instruction is sent from the management server via a relay device to the electric actuator 16. The control unit of the electric actuator 16 drives the motor 40 in response to the received control signal. The driving force of this motor 40 is transmitted to the main gear 42, causing the rotating shaft 46 to rotate together with the main gear 42. As a result, a rotational force is applied to the valve shaft of the water faucet 12, which is fixedly connected to the rotating shaft 46. The valve shaft to which the rotational force is applied is moved up and down by a feed screw mechanism, and the valve disc is moved to a fully open position, a fully closed position, or the like.

[0064] Similarly, in a water outlet 14 equipped with an electric actuator 16, when a user sends an operation instruction to set the outlet height of the water outlet 14 (height position of the partition body 18), the control unit of the electric actuator 16 drives the motor 40 in accordance with the control signal to change the outlet height of the water outlet 14.

[0065] Returning to Figure 1, the field 100 is provided with a water level meter 50 for detecting the water level in the field 100, located near the water supply tap 12 and the water outlet 14. Although not shown, the field 100 may also be provided with sensors as appropriate, such as a water temperature sensor for detecting the temperature of the field water, an air temperature sensor for detecting the air temperature, a humidity sensor for detecting humidity, a pressure sensor for detecting the air pressure, a soil moisture sensor for detecting the soil moisture, and a soil temperature sensor for detecting the soil temperature. The water level meter 50 (sensor body 52, described later) in this embodiment is a water level / water temperature sensor that can detect not only the water level in the field 100 but also its temperature.

[0066] The water level gauge 50 is connected to the electronic board 36 (controller) of the electric actuator 16 by wiring 58 (signal cable) that complies with the RS-485 standard, for example. Sensor information related to the water level and water temperature detected by the water level gauge 50 is input to the electronic board 36 of the electric actuator 16. The power source for operating the water level gauge 50 is power stored in the storage battery 38 of the electric actuator 16, and this power is supplied to the water level gauge 50 from the electronic board 36. Using the solar cell panel 32 and storage battery 38 provided in the electric actuator 16 as the power source for the water level gauge 50 eliminates the need to provide a separate power source such as dry batteries in the water level gauge 50, and eliminates the need for battery replacement, etc. However, the power source for operating the water level gauge 50 can also be provided in the water level gauge 50, or the water level gauge 50 and the electric actuator 16 can be connected wirelessly.

[0067] However, conventional water level gauges, which have sensors that come into direct contact with field water, are prone to impurities adhering to the sensor, which can lead to measurement errors.Furthermore, the sensor easily becomes dirty, requiring frequent maintenance.

[0068] Therefore, in this embodiment, the following configuration is adopted in the water level meter 50 to make the sensor unit less susceptible to contamination and to enable accurate and stable measurement of the water level in the farm field 100. The configuration of the water level meter 50 will be specifically described below with reference to Figs. 3 to 7.

[0069] As shown in Figures 3 and 4, the water level meter 50 includes a sensor body 52 including a sensor unit 60 and an inner cover 62, and a water level meter housing member 54 including a sensor case 70, a shielding membrane 72, a protective member 74, and the like.

[0070] Referring to Figure 5 along with Figures 3 and 4, the sensor main body 52 includes a sensor unit 60 (sensor board) that detects the water level in the farm field 100. The sensor unit 60 can be a known water level sensor, such as a capacitance type, pressure type, electrical resistance type, float type, or ultrasonic type. In this embodiment, a capacitance type sensor formed in the shape of a rectangular plate that is long in the vertical direction is used. The sensor unit 60 is housed in a vertically tubular (cylindrical in this embodiment) inner cover 62, and is fixed therein by screws or the like. The inner cover 62 is a member that surrounds and protects the sensor unit 60, and is made of a synthetic resin such as hard polyvinyl chloride or polyethylene. The nominal diameter (inner diameter) of the inner cover 62 is, for example, 40 mm.

[0071] A circular reference line 62a is provided on the outer peripheral surface of the lower end of the inner cover 62, aligned with the height position of the zero point 60a of the sensor unit 60. When installing the water level meter 50, the height position of this reference line 62a is aligned with the height position of the upper surface (paddy field surface) of the farm field 100. A cylindrical cap 64 with a top is attached to the upper end of the inner cover 62 to seal the upper end opening of the inner cover 62. The lower end of this cap 64 is used as a locking part 64a that is locked to the upper end (support part 70d) of the sensor case 70, which will be described later. The lower end opening of the inner cover 62 is left open and is used as a water passage port 62b, which is an entrance and exit for fresh water C (see FIG. 8), which will be described later, into the inner cover 62.

[0072] 3 and 4 as well as 6 and 7, the water level gauge housing member 54 includes a sensor case 70 in the shape of a vertical tube (cylindrical in this embodiment) that houses the sensor section 60 of the sensor main body 52. ​​The sensor case 70 is made of synthetic resin such as hard polyvinyl chloride and polyethylene. The sensor case 70 is preferably made of transparent resin so that the internal state can be seen.

[0073] The sensor case 70 has an air vent 70a formed in its upper portion and a first water vent 70b formed in its lower portion. The air vent 70a is formed above the upper measurement limit 60b of the sensor unit 60, and the first water vent 70b is formed below the lower measurement limit 60c of the sensor unit 60. In this embodiment, a hole formed in the upper end of the sensor case 70 is used as the air vent 70a, and the lower opening of the sensor case 70 is used as the first water vent 70b. However, the upper opening 70c of the sensor case 70 can also be used as the air vent by forming a notch in the lower end of the cap 64 of the sensor main body 52 or in the upper end of the sensor case 70. Furthermore, the air vent 70a is preferably inclined downward toward the outside to prevent rainwater from entering the sensor case 70.

[0074] The upper end of the sensor case 70 is used as a support portion 70d that supports the lower end (locking portion 64a) of the cap 64 from below. The lower end of the sensor case 70 is tapered, increasing in diameter as it extends downward. That is, the sensor case 70 has a tapered portion 70e at its lower end. By tapering the lower end of the sensor case 70, the fresh water C can flow smoothly into the sensor case 70 when the water level in the shielding membrane 72 rises. The sensor case 70 also has a cylindrical clamping portion 70f that rises from the lower end of the tapered portion 70e. The nominal diameter of the portion of the sensor case 70 above the tapered portion 70e is, for example, 50 mm, and the nominal diameter of the clamping portion 70f is, for example, 100 mm.

[0075] The water level gauge housing member 54 also includes a bag-shaped shielding membrane 72 having an opening 72a at its upper end, the interior of which is in communication with the first water passage port 70b (and thus the interior of the sensor case 70). The shielding membrane 72 is formed into a bag-like shape that can expand and contract (expand and contract) using a water-tight and flexible membrane-like material such as rubber or a synthetic resin such as polyethylene. The inner periphery of the opening 72a is set to be approximately the same as the outer periphery of the clamping portion 70f of the sensor case 70. In this embodiment, a standard polyethylene bag No. 10 (width 180 mm, length 270 mm) is used as the shielding membrane 72. When using a standard polyethylene bag, the thickness of the shielding membrane 72 is preferably 0.06 mm to 0.10 mm, for example, taking into account strength and conformability (expansion and contraction). In this embodiment, the thickness of the shielding membrane 72 is 0.08 mm.

[0076] The opening 72a of the shielding film 72 is watertightly connected to the lower end of the sensor case 70. By connecting the shielding film 72 to the lower end of the sensor case 70, the size of the shielding film 72 (and the protective member 74) can be reduced to the minimum necessary. In this embodiment, the opening 72a of the shielding film 72 is sandwiched and fixed between a clamping portion 70f provided at the lower end of the sensor case 70 and an upper end of a side wall 80 of the protective member 74, which will be described later, so that the opening 72a of the shielding film 72 is watertightly connected to the sensor case 70.

[0077] Furthermore, the water level gauge storage member 54 includes a cylindrical protective member 74 with a bottom that is provided to surround the entire shielding membrane 72. This protective member 74 protects the shielding membrane 72 and also ensures a predetermined space around the shielding membrane 72 (i.e., prevents the shielding membrane 72 from being buried in the soil). The protective member 74 also functions as a restraining member that restrains the shielding membrane 72 to a certain shape when expanded. In this embodiment, the protective member 74 is formed by combining multiple short pipe members and disk members made of synthetic resin such as hard polyvinyl chloride and polyethylene, and fixing them by adhesive, screws, etc. The protective member 74 is preferably formed from a transparent resin so that the internal state (particularly the state of the shielding membrane 72 and the water level) can be seen.

[0078] Specifically, the protective member 74 includes a cylindrical side wall 80 and a disk-shaped bottom wall 82. The nominal diameter of the central portion of the side wall 80 (the portion surrounding the shielding membrane 72) is, for example, 100 mm. A raised bottom portion 80a that protrudes downward from the bottom wall 82 is formed at the lower portion of the side wall 80, and a plurality of mud drainage holes 82a that penetrate the bottom wall 82 in the thickness direction are formed in the bottom wall 82. As a result, even if mud gets into the protective member 74, the mud is discharged from the mud drainage holes 82a below the bottom wall 82, preventing any adverse effects on the operation (expansion / contraction) of the shielding membrane 72.

[0079] Furthermore, a plurality of air vent holes 80b are formed in the upper part of the side wall 80 and are arranged at predetermined intervals in the circumferential direction. These air vent holes 80b also serve as entrances and exits for field water D (see FIG. 9) into the protective member 74. Furthermore, a plurality of second water passage holes 80c are formed in the lower part (raised bottom part 80a) of the side wall 80 and are arranged at predetermined intervals in the circumferential direction. These second water passage holes 80c serve as entrances and exits for field water D into the protective member 74, and are formed at positions below the lower measurement limit position 60c of the sensor unit 60. Furthermore, a marked line 80d is formed on the side wall 80, indicating an appropriate amount of clean water C (described later) (the appropriate water level when there is no field water D around the blocking membrane 72).

[0080] Furthermore, an annular support portion 80e that protrudes inward is formed on the upper inner surface of the side wall 80. When attaching the sensor case 70 and the shielding film 72 to the protective member 74, the opening 72a of the shielding film 72 is sandwiched between the clamping portion 70f of the sensor case 70 and the upper end of the side wall 80, and the lower end of the clamping portion 70f is engaged with the support portion 80e. Then, the upper end of the clamping portion 70f is pressed down from above using screws 88 or the like, thereby fixing the sensor case 70 and the shielding film 72 to the protective member 74. The sensor case 70 and the shielding film 72 can be detached from the protective member 74 by removing the screws 88, facilitating the replacement of the shielding film 72, for example.

[0081] When attaching the sensor main body 52 to the water level gauge housing member 54, the sensor section 60 and inner cover 62 of the sensor main body 52 are inserted through the upper end opening 70c of the sensor case 70, and the lower end (locking section 64a) of the cap 64 is locked onto the upper end (support section 70d) of the sensor case 70. This holds the sensor main body 52 upright in the water level gauge housing member 54 so that the sensor section 60 is positioned at a predetermined height. In other words, the sensor main body 52 is detachable from the sensor case 70, and the sensor main body 52 can be easily attached and detached simply by inserting and removing it from the sensor case 70. The detachability of the sensor main body 52 from the sensor case 70 (water level gauge housing member 54) allows for flexible operation, such as removing only the sensor main body 52 from the field 100 and storing it in a storage shed during agricultural off-seasons such as winter.

[0082] In this embodiment, the height position of the upper end of the side wall 80 of the protective member 74 is aligned with the height position of the marked line 62a of the sensor main body 52 (i.e., the zero point 60a of the sensor unit 60), and when the water level meter 50 is installed in the field 100, the height position of the upper end of the side wall 80 of the protective member 74 is aligned with the height position of the top surface of the field 100.

[0083] 1, such a water level gauge 50 is installed in a manhole 56 provided in the farm field 100 to form a water level gauge installation structure 120. That is, the water level gauge installation structure 120 includes the water level gauge 50 and a manhole 56 provided so as to surround the water level gauge 50.

[0084] The manhole 56 is formed in a cylindrical shape with a bottom, and is erected in the field 100 by embedding its lower end in the field 100. A plurality of holes penetrating in the thickness direction are formed in the side walls and bottom wall of the manhole 56 and distributed throughout the entire pipe wall. The plurality of holes are used as inlets and outlets for the field water D into the manhole 56. The height position of the bottom surface (top surface of the bottom wall) of the manhole 56 is set at a position where, when the water level meter 50 is installed in the manhole 56, the zero point 60a of the sensor unit 60 coincides with the height position of the upper surface of the field 100. In addition, the height position of the upper end of the side wall of the manhole 56 is set at a position equal to or slightly above the maximum water level of the field water D that can be stored in the field 100.

[0085] When the water level meter 50 is installed in the field 100, fresh water C is stored inside the blocking membrane 72 (see FIG. 8). The blocking membrane 72 is also provided so that its outer surface comes into contact with field water D. In this embodiment, the field water D that has flowed into the manhole 56 passes through the second water passage port 80c and the mud drainage port 82a of the protective member 74 and reaches the periphery of the blocking membrane 72, thereby bringing the outer surface of the blocking membrane 72 into contact with the field water D.

[0086] The amount of fresh water C is set to a value greater than the spatial volume within the sensor case 70 below the upper measurement limit 60b of the sensor unit 60 (i.e., from the upper measurement limit 60b to the bottom end of the sensor case 70) (the volume of the spatial portion excluding the volume of the sensor unit 60 and the inner cover 62). The amount of fresh water C is set so that the water level (upper surface) of the fresh water C is equal to or lower than the lower measurement limit 60c of the sensor unit 60 when there is no field water D around the shielding membrane 72. Note that the term "fresh water C" in this invention refers to water such as tap water that does not contain impurities (foreign matter) such as mud, straw, and fallen leaves. Therefore, agricultural water or the like can also be used as the fresh water C as long as it is free of impurities (or has been removed). To prevent slime formation due to bacterial proliferation, a slime inhibitor or the like can be mixed into the fresh water C, provided that it does not affect water level measurement.

[0087] When filling the inside of the blocking membrane 72 with fresh water C, it is advisable to visually confirm that the fresh water C has been filled up to the position of the marked line 80d on the protective member 74. However, if the protective member 74 is not transparent, it is also possible to form a hole (peephole) in the side wall 80 at a position that indicates the appropriate amount of fresh water C, and visually confirm that the fresh water C has been filled up to the position of the hole. Alternatively, it is possible to form a hole in the side wall 80 at a position that indicates the appropriate amount of fresh water C, and to provide a small valve in the hole that communicates with the inside of the blocking membrane 72. In this case, the appropriate amount of fresh water C is filled by filling the tank with the valve open, and closing the valve when fresh water C starts to leak out from the valve.

[0088] Next, the operation of the water level meter 50 will be described with reference to Figures 8 to 10. As shown in Figure 8, when there is no field water D around the blocking membrane 72, or when the level of the field water D is lower than the appropriate level (i.e., the lowest level) of the clear water C when there is no field water D around the blocking membrane 72, the clear water C maintains its lowest level, and the blocking membrane 72 is in a maximum expanded state. At this time, the protective member 74 constrains the shape of the blocking membrane 72 (the expanded shape) to a fixed shape. This stabilizes the expanded shape of the blocking membrane 72, and therefore stabilizes the minimum level of the clear water C. Furthermore, because the water pressure inside the blocking membrane 72 is received by the protective member 74, no force is applied to the blocking membrane 72, improving the durability of the blocking membrane 72.

[0089] 9, when the level of the field water D rises above the lowest level of the fresh water C, the shielding membrane 72 contracts (shrinks) due to the water pressure of the field water D that flows around the shielding membrane 72 through the second water port 80c and the mud drain port 82a. As a result, the level of the fresh water C rises, and the fresh water C flows into the sensor case 70 and the inner cover 62, i.e., around the sensor unit 60. At this time, air that had accumulated in the protective member 74 is discharged through the air vent 80b, and air that had accumulated in the sensor case 70 and the shielding membrane 72 is discharged through the ventilation port 70a. As a result, the air in the sensor case 70 and the shielding membrane 72 is either maintained at atmospheric pressure or completely discharged. When the internal and external pressures acting on the shielding membrane 72 reach equilibrium, i.e., when the levels of the fresh water C and the field water D are equal, the shielding membrane 72 stops contracting.

[0090] 10, the level of the fresh water C and the level of the field water D are kept equal until the level of the field water D reaches or exceeds the upper measurement limit position 60b of the sensor unit 60. When the level of the field water D drops, the water pressure of the fresh water C causes the shielding membrane 72 to expand. As a result, the level of the fresh water C drops, and when the level of the fresh water C and the level of the field water D become equal, the expansion of the shielding membrane 72 stops. At this time, air flows into the protective member 74 through the air vent 80b and into the sensor case 70 and the shielding membrane 72 through the ventilation opening 70a, so that the air inside the sensor case 70 and the shielding membrane 72 is maintained at atmospheric pressure.

[0091] That is, in the water level meter 50, the blocking membrane 72 expands and contracts in accordance with fluctuations in the water level of the field water D, thereby maintaining a state in which the water level of the fresh water C matches the water level of the field water D. Therefore, by detecting the water level of the fresh water C with the sensor unit 60, the water level of the field water D (field 100) can be detected.

[0092] As described above, according to this embodiment, the water level of the farm field 100 is detected by using the shielding membrane 72 that stores fresh water inside and bringing fresh water C, rather than field water D, into contact with the sensor unit 60. Therefore, the sensor unit 60 is less likely to become soiled, and the water level of the farm field 100 can be measured accurately and stably. Furthermore, because the sensor unit 60 is less likely to become soiled, the maintenance frequency of the water level meter 50 can be significantly reduced.

[0093] Furthermore, according to this embodiment, the protective member 74 surrounding the shielding membrane 72 is provided, so the shielding membrane 72 is appropriately protected and can be operated (expanded / contracted) appropriately. Furthermore, since the water level gauge 50 is installed in the manhole 56, the water level gauge 50 itself is also appropriately protected, and the manhole 56 can prevent large debris, mud, etc. from entering around the water level gauge 50, making it possible to make the sensor unit 60 even more resistant to contamination.

[0094] Next, a water level meter 50 according to another embodiment of the present invention will be described with reference to Fig. 11. Note that parts common to the above-described embodiment (the embodiment shown in Fig. 1) will be given the same reference numerals, and duplicated explanations will be omitted or simplified. Omission of duplicated explanations will also be applied to other embodiments described later.

[0095] In the embodiment shown in FIG. 11 , the shielding film 72 is provided to cover the lower part of the sensor case 70, and an opening 72a of the shielding film 72 is connected to the center or upper part of the sensor case 70 in a watertight manner. The sensor case 70 also has an air vent 70g (second air vent) formed directly below the connection position with the shielding film 72. This air vent 70g is used as an air vent for releasing air that has accumulated above the shielding film 72 when the shielding film 72 contracts. The air discharged from the air vent 70g is exhausted to the outside through the air vent 70a of the sensor case 70. When the shielding film 72 expands, external air is drawn into the shielding film 72 through the air vents 70a and 70g. This maintains the air inside the shielding film 72 at atmospheric pressure, allowing the shielding film 72 to operate (expand or contract) appropriately.

[0096] The protective member 74 includes a cylindrical side wall 80, a disk-shaped bottom wall 82, and an annular plate-shaped top wall 84, and is provided so as to surround the entire shielding membrane 72. The top wall 84 is formed with an air vent 84a, and the side wall 80 is formed with a second water passage 80c at a position below the lower measurement limit position 60c of the sensor unit 60.

[0097] In the embodiment shown in Figure 11, as in the embodiment shown in Figure 1, the water level of the field 100 is detected by bringing clean water C into contact with the sensor unit 60, which makes it difficult for the sensor unit 60 to become dirty and allows the water level of the field 100 to be measured accurately and stably.

[0098] In the embodiment shown in Fig. 1, the sensor main body 52 is provided with an inner cover 62, but as in the embodiment shown in Fig. 11, the sensor main body 52 does not necessarily have to be provided with the inner cover 62. Furthermore, the water level meter 50 does not necessarily have to be installed inside the manhole 56, and as in the embodiment shown in Fig. 11, the water level meter 50 can also be installed in a dug hole or the like provided in the farm field 100. Furthermore, in the embodiment shown in Fig. 1, the manhole 56 is formed into a cylindrical shape with a bottom, but the manhole 56 does not necessarily have to have a bottom wall.

[0099] Furthermore, although not shown, the central portion of the lower end of the shielding film 72 can also be connected (fixed) to the bottom wall 82 of the protective member 74. This causes the expansion / contraction (deformation) direction of the shielding film 72 to be horizontal, and the lower end of the shielding film 72 does not deform to float (separate) from the bottom wall 82. This makes it difficult for mud to accumulate between the lower end of the shielding film 72 and the bottom wall 82, and also prevents air from becoming trapped. This prevents the accumulated mud and trapped air from adversely affecting the operation (expansion / contraction) of the shielding film 72.

[0100] Furthermore, as in the embodiment shown in FIG. 12 , the water level gauge 50 (or the water level gauge housing member 54) can also be provided with a second shielding membrane 90 and a second protective member 92. The second shielding membrane 90 is formed in a bag shape with an opening, and the opening is airtightly connected to the ventilation hole 70a so as to communicate with the inside of the sensor case 70. Like the shielding membrane 72, the second shielding membrane 90 is formed from a standard polyethylene bag or the like so as to be able to expand and contract. The volume of this second shielding membrane 90 when expanded is set to be larger than the spatial volume within the sensor case 70. Furthermore, the second protective member 92 is provided so as to entirely surround the second shielding membrane 90. The second protective member 92 has a ventilation hole 92a (third ventilation hole) formed at a predetermined position.

[0101] 12, when the shielding membrane 72 contracts and the level of the fresh water C rises, the air inside the sensor case 70 and the shielding membrane 72 flows into the second shielding membrane 90 through the ventilation hole 70a, causing the second shielding membrane 90 to expand. On the other hand, when the shielding membrane 72 expands and the level of the fresh water C drops, the air inside the second shielding membrane 90 flows into the sensor case 70 and the shielding membrane 72, causing the second shielding membrane 90 to contract. In this way, the air inside the sensor case 70 and the shielding membrane 72 simply moves inside the sensor case 70, the shielding membrane 72, and the second shielding membrane 90 without being discharged to the outside. This prevents the fresh water C from decreasing due to evaporation (a decrease in the amount of fresh water), making it unnecessary to replenish the fresh water C.

[0102] 13, a horizontal pipe section 86 can also be provided on the protective member 74. The horizontal pipe section 86 protrudes laterally from the side wall 80 and is provided so as to extend into a dug hole 130 (or a pit) provided in the field 100 at a position away from the sensor main body 52. ​​The tip end (tip opening) of the horizontal pipe section 86 serves as a second water passage port 86a, which is an entrance / exit for the field water D into the protective member 74. The length of the horizontal pipe section 86 is set to, for example, 3 m to 10 m.

[0103] According to the embodiment shown in Figure 13, field water D can be drawn from a position away from the sensor main body 52 installed in a peripheral position of the water tap 12, that is, a stable water level can be detected at a position that is less affected by water level fluctuations during water supply, thereby further improving the detection accuracy of the water level meter 50.

[0104] 14, a horizontally tubular extension 70h extending laterally can be formed at the bottom of the sensor case 70. The extension 70h extends into a borehole 130 (or a manhole) formed in the farm field 100 at a position away from the sensor main body 52, and a first water passage port 70b is formed at the tip of the extension 70h. The length of the extension 70h is set to, for example, 3 m to 10 m. The shielding film 72 and the protective member 74 are disposed in the borehole 130 and are connected to the tip of the extension 70h (i.e., the lower end of the sensor case 70) within the borehole 130.

[0105] According to the embodiment shown in FIG. 14, similar to the embodiment shown in FIG. 13, a stable water level can be detected at a position that is less susceptible to the influence of water level fluctuations during water supply, thereby further improving the detection accuracy of the water level meter 50.

[0106] In the embodiment shown in Figure 14, the tip of the extension portion 70h is connected to the upper ends of the shielding film 72 and the protective member 74, but as shown in Figure 15, the tip of the extension portion 70h can also be connected to the side of the shielding film 72 and the protective member 74.

[0107] The specific configurations of the sensor body 52, water level gauge housing member 54 (sensor case 70, shielding membrane 72, protective member 74, etc.) and manhole 56 shown in the above-mentioned embodiments are merely examples and can be modified as appropriate.

[0108] For example, the protective member 74 can be formed using a Netron (registered trademark) pipe or Netron sheet, which has a mesh structure with numerous holes formed in the pipe wall. The shapes of the shielding film 72 and the protective member 74 can also be modified as appropriate; for example, increasing the width (diameter) of the shielding film 72 and the protective member 74 can reduce their vertical length. Furthermore, the protective member 74 does not necessarily have to be provided so as to surround the entire shielding film 72; for example, it may be provided so as to cover only the lower half of the shielding film 72. Furthermore, the protective member 74 does not necessarily have to be provided as long as a predetermined space can be secured around the shielding film 72.

[0109] Furthermore, in each of the above-described embodiments, the sensor case 70 (and inner cover 62) is formed in a cylindrical shape, but the shape of the sensor case 70 (and inner cover 62) is not particularly limited as long as it can secure the water area necessary for measurement by the sensor unit 60 used. In this case, by adopting a shape that reduces the internal volume of the sensor case 70, the shielding membrane 72 can be made smaller, and ultimately the water level gauge 50 can be made smaller.

[0110] 16 and 17, when a sensor formed as a vertically long rectangular plate, such as a capacitance-type or electrical resistance-type sensor, is used as the sensor unit 60, the sensor case 70 may be formed as a rectangular cylinder that fits along the outer surface of the sensor unit 60 with a predetermined gap between them. By forming the sensor case 70 as a rectangular cylinder, as in the embodiment shown in FIG. 16, the internal volume can be reduced, and the shielding membrane 72 can also be made smaller. This allows the water level gauge 50 to be made more compact.

[0111] However, if the passage for the fresh water C inside the sensor case 70 (the gap X between the outer surface of the sensor unit 60 and the inner surface of the sensor case 70) becomes too small, there is a risk that the water surface inside the sensor case 70 will rise or fall below the surrounding water surface due to capillary action. As a result of testing by the inventors, it was found that the effect of capillary action is almost eliminated when the size of the gap X is 3 mm or larger, so in this embodiment, the gap X is set to 5 mm to allow for some leeway. Furthermore, the effect of capillary action can be reduced by using a material for the sensor case 70 that has a contact angle of close to 90 degrees when it comes into contact with water (for example, polyethylene with a contact angle of about 100 degrees, or rigid polyvinyl chloride with a contact angle of about 75 degrees). Furthermore, since the sensor case 70 is made of a material whose contact angle with water is significantly different from 90 degrees, even if a large water level difference occurs between the water surface inside the sensor case 70 and the surrounding water surface, if the cross-sectional shape of the sensor case 70 is kept the same in the vertical direction, the water level difference will be constant, and this can be addressed by making a correction to subtract the water level difference from the measurement value.

[0112] In the embodiment shown in FIG. 16 , the sidewall 80 of the protective member 74 is provided to entirely surround the shielding membrane 72 and the sensor case 70. A flange-shaped mounting portion 70i for mounting the shielding membrane 72 is formed at the lower end of the sensor case 70, and the opening 72a of the shielding membrane 72 is watertightly connected to the lower end of the sensor case 70. The upper opening of the sensor case 70 is sealed by a canopy 70j having an air vent 70a. A second shielding membrane 90 is connected to the air vent 70a via a connecting pipe 94. A second protective member 92 having a topped vertical cylinder shape is connected to the upper end of the sidewall 80 of the protective member 74. The upper end of the sensor unit 60 (the non-measurement portion above the upper measurement limit position 60b) is provided to penetrate the canopy 70j and protrude upward. However, the portion where the upper end of the sensor unit 60 penetrates the canopy 70j is airtightly sealed.

[0113] 18 and 19, when a pressure-type sensor formed in a short cylindrical shape is used as the sensor unit 60, the sensor case 70 may have any shape that allows the sensor unit 60 and a connector (not shown) to pass through. In the embodiment shown in FIG. 18, the sensor unit 60 is housed in the lower end of the sensor case 70. The wiring 58 is arranged to pass through the sensor case 70 and penetrate the canopy 70j. In this case, since the wiring 58 is thinner (has a smaller cross-sectional area) than the sensor unit 60, an appropriate water area necessary for transmitting water pressure is secured around the wiring 58. However, the portion where the wiring 58 penetrates the canopy 70j is airtightly sealed. In the embodiment shown in FIG. 18, the sensor case 70 may have any shape that allows the sensor unit 60 and a connector to pass through, thereby reducing its internal volume. This allows the size of the shielding membrane 72 to be reduced, thereby enabling the water level gauge 50 to be miniaturized.

[0114] 18, the wiring 58 is passed through the inside of the sensor case 70, but as shown by the dashed line in Fig. 18, the wiring 58 may be passed out from the bottom of the sensor case 70. However, the portion where the wiring 58 passes through the sensor case 70 is made airtight.

[0115] Furthermore, in each of the above-described embodiments, the opening 72a of the shielding membrane 72 is connected to the sensor case 70 in a watertight manner, but this is not limiting. For example, if the shielding membrane 72 is provided to cover the periphery of the sensor case 70 and the opening 72a is located above the maximum water level of the field water D that can be stored in the field 100, the opening 72a can be left open without being connected to the sensor case 70. In this case, however, a cover or eave must be provided to cover the upper part of the opening 72a in order to prevent rainwater and the like from entering the shielding membrane 72.

[0116] Furthermore, in each of the above-described embodiments, the water level gauge 50, the sump 56, etc. are provided within the cultivated area of ​​the field 100 divided by the ridges 102, but this is not limiting. Although not shown, it is also possible to excavate the ridges 102 or the like to provide a field extension section on the ridges 102 that communicates with the cultivated area of ​​the field 100, and to provide the water level gauge 50, the sump 56, etc. in this field extension section.

[0117] It should be noted that the specific values ​​of the dimensions and the specific shapes given above are merely examples and can be changed as appropriate according to the needs of the product specifications and the like. [Explanation of symbols]

[0118] 10...Field water management system 12...Water tap 14...Ochimizuguchi 16... Electric actuator 50…Water level gauge 52 ...Sensor body 54...Water level gauge storage component 60...Sensor section 62...Inner cover 62a...Water outlet 70...Sensor case 70a...vent 70b…1st water outlet 70h...extension part 70g ... Second vent 72...Occluded membrane 72a...opening 74...Protective material 80a... bottom raised part 80b, 84a ... Air vent 80c,86a…2nd water outlet 82a ... Mud drainage port 90...Second shielding membrane 92 ... Second protective member 92a...Third vent 100...field 102 …Round 120...Water level gauge installation structure

Claims

1. A water level meter for detecting the water level in a field, a sensor body having a sensor portion for detecting the water level; a vertically tubular sensor case having an air vent formed in an upper portion and a first water vent formed in a lower portion, the sensor case accommodating the sensor unit; a sealing membrane formed in an inflatable bag shape having an opening, the inside of which is provided in communication with the first water passage port; A water level meter in which fresh water is stored inside the blocking membrane and the blocking membrane is provided so that its outer surface comes into contact with field water.

2. The water level meter according to claim 1 , wherein the opening of the shielding membrane is watertightly connected to the sensor case.

3. the vent hole is formed at a position above an upper measurement limit position of the sensor unit, The water level meter according to claim 1 or 2, wherein the first water passage port is formed at a position below a lower measurement limit position of the sensor unit.

4. 3. The water level gauge according to claim 1, further comprising a second water passage opening that opens at a position lower than the lower measurement limit position of the sensor unit, and a bottomed cylindrical protective member that is provided to surround the blocking membrane.

5. The water level meter according to claim 4 , wherein the protective member is provided so as to surround the entirety of the shielding film.

6. The water level meter according to claim 5 , wherein the protective member has an air vent formed in an upper portion thereof.

7. 5. The water level gauge according to claim 4, wherein the protective member has a bottom-raised portion provided at a lower portion of the side wall and a mud drain port formed in the bottom wall.

8. The water level meter according to claim 1 or 2, wherein the opening of the shielding film is connected to a lower end of the sensor case.

9. The water level meter according to claim 8 , wherein the lower end of the sensor case is formed in a tapered shape that increases in diameter downward.

10. The water level meter according to claim 4 , wherein a lower end of the shielding film is connected to a bottom wall of the protection member.

11. The protective member has a horizontal tube portion that protrudes laterally, The water level meter according to claim 5 , wherein the second water passage port is formed at a tip end of the horizontal pipe portion.

12. the sensor case has a horizontally tubular extending portion at a lower portion thereof, The water level meter according to claim 1 or 2, wherein the first water passage port is formed at a tip end of the extension portion.

13. The water level meter according to claim 1 or 2, wherein the sensor body is detachably provided in the sensor case.

14. The water level meter according to claim 1 or 2, wherein the sensor body includes an inner cover for protecting the sensor portion.

15. 3. The water level meter according to claim 1, wherein the amount of fresh water is greater than a volume of space within the sensor case below an upper measurement limit position of the sensor unit.

16. the shielding film is provided to cover a lower portion of the sensor case, The water level gauge according to claim 2 , wherein the sensor case has a second vent hole formed immediately below the position where the sensor case is connected to the shielding film.

17. a second shielding membrane formed in an expandable and contractible bag shape and airtightly connected to the ventilation hole; and The water level gauge according to claim 2 , further comprising a second protection member having a third vent hole and provided so as to surround the second shielding membrane.

18. The water level gauge according to claim 4 , wherein the protective member restricts the shape of the shielding membrane to a fixed shape when expanded.

19. The sensor unit is formed in a rectangular plate shape, The water level meter according to claim 1 or 2, wherein the sensor case is formed in a rectangular cylindrical shape that fits along the outer surface of the sensor unit with a predetermined gap therebetween.

20. 3. The water level meter according to claim 1, wherein the sensor unit is a pressure-type sensor and is housed in a lower end portion of the sensor case.

21. A water level meter housing member that constitutes a water level meter that detects the water level of a field together with a sensor main body having a sensor unit, a vertically tubular sensor case having an air vent formed in an upper portion and a first water vent formed in a lower portion, the sensor case accommodating the sensor unit; A water level gauge storage member formed in the shape of an expandable and contractible bag having an opening, the interior of which is provided with a blocking membrane arranged to communicate with the first water passage port.

22. An installation structure for a water level meter that detects the water level in a field, The water level meter according to claim 1, and A water level gauge installation structure comprising a cylindrical or bottomed cylindrical manhole having a plurality of holes penetrating in the thickness direction and installed in the field so as to surround the water level gauge.

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