JP7572931B2 - Water level sensor installation structure - Google Patents

Description

Patent Law Article 30, Paragraph 2 application Explanatory meeting for test installation (Hokuriku Regional Agricultural Administration Office, Sekigawa Waterworks Agricultural Waterworks Office) held on February 16, 2021 [Publications, etc.] Explanatory meeting for users of test installation (Joetsu City, Niigata Prefecture) held on March 1, 2021 [Publications, etc.] Joetsu City, Niigata Prefecture Installation on April 26, 2021

This invention relates to a water level sensor installation structure, and in particular to a water level sensor installation structure for detecting the water level in a farm field.

One example of a conventional installation structure for this type of water level sensor 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 the housing of the water level sensor (sensor terminal) is connected and fixed to the single pipe using a swivel clamp or the like, thereby erecting the water level sensor in the field.

JP 2020-103099 A

In the technology of Patent Document 1, the readings of the water level sensor vibrate due to the effects of waves generated in the water supply when water is supplied from the water tap or during strong winds, and in some cases the water level in the field cannot be accurately measured (detected). In addition, because the water level sensor is plunged into the field, soil can get into the water level sensor housing and adhere to the sensor, resulting in erroneous measurements.

Therefore, the primary objective of this invention is to provide a novel water level sensor installation structure.

Another object of the invention is to provide a water level sensor installation structure that can improve the detection accuracy of the water level sensor.

The first invention is an installation structure for a water level sensor that detects the water level in a field, comprising a water level sensor that has a sensor unit that detects the water level in the field by using changes in the capacitance or pressure of the field water and a vertical cylindrical housing that houses the sensor unit, a protective tube that has a plurality of holes penetrating in the thickness direction and is erected with its lower end embedded in the field so as to surround the housing, and an installation base that has a sensor holding part that holds the housing.

In a first invention, the installation structure for the water level sensor comprises a water level sensor, a protective tube, and an installation stand. The water level sensor comprises a sensor unit that detects the water level in the field, and a vertical cylindrical housing that houses the sensor unit. The protective tube is erected in the field with its lower end embedded in the field, and is provided so as to surround the housing of the water level sensor. The protective tube has multiple holes that penetrate in the thickness direction, and these multiple holes are used as inlets and outlets for the water. The installation stand has a sensor holding part that holds the housing.

According to the first invention, the water level sensor is surrounded by a protective tube, so that the water level sensor is less susceptible to the effects of waves that occur during water supply or strong winds, and the readings of the water level sensor can be stabilized. In addition, by surrounding the water level sensor with a protective tube and supporting it with an installation stand, the water level sensor is prevented from being buried in the soil, and erroneous measurements caused by soil adhering to the sensor portion can be prevented. Therefore, the detection accuracy of the water level sensor can be improved.

The second invention is dependent on the first invention, and the lower end of the housing is removably fitted into the sensor holding portion.

According to the second invention, the water level sensor can be accurately installed simply by fitting the lower end of the housing into the sensor holding portion. In other words, the installation of the water level sensor is made easier and the installation accuracy of the water level sensor can be improved. In addition, the water level sensor can be removed simply by pulling out the lower end of the housing from the sensor holding portion. In other words, removal of the water level sensor is also made easy.

The third invention is dependent on the second invention, and the protective tube is formed into a bottomed tube having a side wall and a bottom wall. The installation base is attached to the bottom wall.

The fourth invention is according to the second or third invention, and the mounting stand is provided so that the height position of the sensor holding portion can be adjusted.

According to the fourth invention, the water level sensor can be installed more accurately.

The fifth invention is dependent on any one of the second to fourth inventions, and further includes a positioning member that is provided to connect the upper end of the protective tube to the upper end of the housing, and prevents the housing from shifting sideways relative to the protective tube.

According to the fifth invention, lateral shift (tilt) of the upper end of the water level sensor can be reliably prevented, thereby further improving the installation accuracy and detection accuracy of the water level sensor.

The sixth invention is dependent on the first invention, and the installation stand has a sensor holding part that holds the upper end of the housing, and a connecting part that connects the sensor holding part to the upper end of the protective tube.

The seventh invention is dependent on any one of the first to sixth inventions, and further includes a mud filter provided on the inner peripheral surface of the protective tube to prevent mud from entering the protective tube through the multiple holes.

According to the seventh invention, it is possible to prevent mud from entering the protective tube, thereby preventing erroneous measurements caused by mud adhering to the sensor part of the water level sensor.

The eighth invention is dependent on any one of the first to seventh inventions and further includes an anchor protruding outward from the protective tube.

According to the eighth invention, even if the protective tube is erected in a soft field, it is possible to prevent the protective tube from floating up and tilting, thereby improving the installation accuracy of the protective tube (and therefore the water level sensor) in the field.

The ninth invention is dependent on any one of the first to eighth inventions, and further includes a cover that covers the upper opening of the protective tube.

According to the ninth invention, even if foreign matter such as grass pieces and soil are scattered during weeding and plowing, the scattered foreign matter is prevented from entering the protective tube. Therefore, it is possible to prevent erroneous measurements caused by foreign matter such as grass pieces and soil adhering to the sensor part of the water level sensor, and the detection accuracy of the water level sensor can be further improved.

The tenth invention is dependent on any one of the first to ninth inventions, and the field includes a field extension section provided on a ridge that divides the field. The water level sensor installation structure is provided in the field extension section.

According to the tenth invention, the water level sensor is less susceptible to the effects of water level fluctuations during water supply, thereby improving the detection accuracy of the water level sensor. In addition, because the installation state of the protective tube and the installation stand is stable, the water level sensor can be installed more accurately in the same position even if it is removed and reinstalled during the agricultural off-season, etc. Furthermore, because it does not extend into the cultivated area of the field, the water level sensor and the like are less likely to interfere with agricultural work.

This invention makes the water level sensor less susceptible to the effects of waves that occur during water supply or strong winds, and also prevents erroneous measurements caused by soil adhering to the sensor, thereby improving the detection accuracy of the water level sensor.

The above and other objects, features and advantages of the present invention will become more apparent from the detailed description of the embodiments given below with reference to the drawings.

1 is a diagram showing a field water management system to which a water level sensor installation structure according to an embodiment of the present invention is applied; FIG. 2 is a cross-sectional view showing the internal structure of the electric actuator. FIG. 2 is a diagram showing a water level sensor. FIG. 1 is a cross-sectional view showing a water level sensor installation structure; FIG. 4 is a cross-sectional view showing the protective tube and the installation base. FIG. 2 is a perspective view showing the appearance of a protective tube. FIG. 11 is a cross-sectional view showing an installation structure of a water level sensor according to another embodiment of the present invention. FIG. 11 is a cross-sectional view showing an installation structure of a water level sensor according to still another embodiment of the present invention. FIG. 11 is a cross-sectional view showing an installation structure of a water level sensor according to still another embodiment of the present invention.

Referring to FIG. 1, a water level sensor installation structure 60 (hereinafter simply referred to as "installation structure 60") according to one embodiment of the present invention is applied when installing a water level sensor 50 in a field water management system 10 (hereinafter simply referred to as "system 10"). As will be described in detail later, this installation structure 60 includes a water level sensor 50 that detects the water level of the field 100, and the water level sensor 50 is surrounded by a protective tube 62 and supported by an installation stand 64, thereby improving the detection accuracy of the water level sensor 50.

First, before providing a detailed description of the installation structure 60, an example of the configuration of the system 10 will be briefly described. However, the configuration of the system 10 (such as the configuration of the water tap 12, the water outlet 14, and the electric actuator 16) is not limited to this example and can be modified as appropriate.

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

In this embodiment, the system 10 includes a plurality of cultivated areas divided by ridges 102. The water taps 12 and the water outlets 14 are installed in each cultivated area, and the electric actuators 16 attached to them are wirelessly connected to a repeater (parent unit) by a wireless communication method conforming to a specific low-power wireless standard (920 MHz band). Each electric actuator 16 is then wirelessly connected to a remote control terminal such as a smartphone, tablet terminal, PDA, or PC owned by the user via the repeater and a management server or the like installed on the network. However, the electric actuators 16 may also wirelessly communicate with external devices such as the management server or remote control terminal without going through the repeater.

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

The water supply faucet 12 is a water supply device for controlling the water supply from the water pipeline 106 to the cultivated area (field 100), and has a displacement mechanism including a valve shaft and a valve body. In this embodiment, a water supply faucet 12 is used that moves up and down with the rotation of the valve shaft, which is a common type. The water supply faucet 12 is placed in a water supply basin 104 provided on the ridge 102, and is attached to the downstream end of a branch pipe 108 that branches off from the water pipeline 106 laid under the ridge 102 and extends into the field 100. An electric actuator 16 is attached to the water supply faucet 12, and the displacement mechanism (valve shaft and valve body) of the water supply faucet 12 is operated by the electric actuator 16.

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 body. In this embodiment, a water outlet 14 with a water level setting function is used. To put it simply, the water outlet 14 has a cylindrical partition body 18 whose upper end opening functions as a drainage outlet, and the partition body 18 moves up and down to adjust the drainage outlet to any height. Such a water outlet 14 is placed in a drainage basin 110 provided on the ridge 102, and is attached to the upstream end of a drainage pipe 114 that extends to a drainage channel 112. An electric actuator 16 is attached to the water outlet 14, and the displacement mechanism (partition body) of the water outlet 14 is moved up and down by the electric actuator 16. However, when attaching the electric actuator 16 to the water outlet 14, an adapter 20 is used that can convert the rotational force of the electric actuator's rotation shaft 46 (see FIG. 2) into a force in the vertical direction (axial direction) and transmit it to the partition body.

Referring to FIG. 2 together with FIG. 1, the electric actuator 16 has a cylindrical main body case 30. A solar panel 32 is removably attached to the top of the main body case 30. The solar panel 32 is supported at a predetermined angle by a metal holder 34 in the form of a bent plate.

The main body case 30 also contains an electronic board 36, a storage battery 38, and a drive mechanism including a motor 40 and a main gear 42.

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 sensor 50, and other components are electrically connected to the control unit. The CPU of the control unit is responsible for the overall control of the electric actuator 16, and controls the driving of the motor 40, etc. The memory is a comprehensive reference to ROM, RAM, HDD, etc., and stores a control program that controls 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 wireless communication is performed with external devices such as a repeater via this antenna.

The storage battery 38 stores the electricity generated by the solar panel 32. The motor 40 is driven by the electricity 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 the driving force from the motor 40 and rotates around its axis.

The main gear 42 is a double-boss type gear, and a roughly cylindrical rotating shaft 46 is inserted into the shaft portion of the main gear 42. A coupling portion 46a that is connected to the valve shaft of the water supply faucet 12 is formed at the lower end of this rotating shaft 46. 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 that 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.

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, and a selection button for switching the operating mode of the electric actuator 16 (remote mode, automatic mode, manual mode, etc.). The operation panel 48 is also provided with a connection terminal for connecting the wiring 58 extending from the water level sensor 50.

In the water tap 12 equipped with the electric actuator 16 as described above, for example, when a user accesses a management server using a remote control terminal and transmits an operation instruction (control signal) to fully close, fully open, or open the water tap 12 to an arbitrary degree, a control signal corresponding to the operation instruction is transmitted from the management server to the electric actuator 16 via a repeater. The control unit of the electric actuator 16 drives the motor 40 in response to the received control signal. The driving force of the motor 40 is transmitted to the main gear 42, and the rotating shaft 46 rotates together with the main gear 42. As a result, a rotational force is applied to the valve shaft of the water tap 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 the feed screw mechanism, and the valve body is moved to a fully open position, a fully closed position, or the like.

Similarly, in a water outlet 14 to which an electric actuator 16 is attached, when a user transmits an operation command to set the drain 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 response to the control signal to change the drain height of the water outlet 14.

Returning to FIG. 1, water level sensors 50 (sensor terminals) are provided in the field 100 at positions around the water taps 12 and the water outlets 14. The water level sensors 50 may be sensors that measure the field water level by utilizing changes in capacitance or pressure of the irrigation water (field water), for example.

Briefly, the water level sensor 50, as shown in FIG. 3, has a vertical cylindrical housing 52 made of synthetic resin such as polyvinyl chloride. The nominal diameter (inner diameter) of the housing 52 is, for example, 40 mm. A sensor unit 54 (sensor board) that detects the water level of the field 100 is housed in the housing 52 and is fixed by screws or the like. A slit 52a that serves as an inlet and outlet for irrigation water is formed at the lower end of the housing 52 so as to extend in the vertical direction. In addition, a ring-shaped mark 52b is provided on the outer peripheral surface of the lower end of the housing 52, and when the water level sensor 50 is installed, the height position of the mark 52b is aligned with the height position of the top surface (paddy field surface) of the field 100. Furthermore, a cap 56 (see FIG. 4) that seals the upper end opening of the housing 52 is provided at the upper end of the housing 52.

Although not shown in the figures, the field 100 may be appropriately provided with sensors such as a water temperature sensor that detects the temperature of the irrigation water, an air temperature sensor that detects the air temperature, a humidity sensor that detects the humidity, a pressure sensor that detects the air pressure, a soil moisture sensor that detects the soil moisture, and a soil temperature sensor that detects the soil temperature. As the water level sensor 50 in this embodiment, a water level and water temperature sensor that can detect not only the water level in the field 100 but also its water temperature is used.

Such a water level sensor 50 is connected to the electronic board 36 of the electric actuator 16 by wiring 58 (signal cable) that complies with the RS-485 standard, for example. Then, sensor information regarding the water level and water temperature detected by the water level sensor 50 is input to the electronic board 36 of the electric actuator 16. In addition, the power stored in the storage battery 38 of the electric actuator 16 is used as the power source for operating the sensor section 54 of the water level sensor 50, and this power is supplied from the electronic board 36 to the water level sensor 50. By using the solar panel 32 and storage battery 38 provided in the electric actuator 16 as the power source for the water level sensor 50, it is no longer necessary to provide a separate power source such as a dry cell battery for the water level sensor 50, and the trouble of battery replacement is no longer necessary.

Here, since the water level sensor 50 is connected to the electric actuator 16 by the wiring 58 as described above, it is preferable to install it in the vicinity of the electric actuator 16. However, if the water level sensor 50 is installed near the water supply tap 12, the reading of the water level sensor 50 may vibrate due to waves generated during water supply, and the water level of the field 100 may not be detected accurately. The same can be said about waves generated during strong winds. In addition, soil may enter the housing 52 through the slit 52a and adhere to the sensor part 54, resulting in an erroneous measurement of the water level. Furthermore, since the water level sensor 50 is installed on unstable soil, there is a demand for improving the installation accuracy of the water level sensor 50.

Therefore, in this embodiment, the detection accuracy of the water level sensor 50 is improved by adopting the installation structure 60 described below. The configuration of the installation structure 60 will be described in detail below with reference to Figures 4 to 6.

As shown in FIG. 4, the installation structure 60 includes a water level sensor 50, a protective tube 62 erected in the field 100 so as to surround the water level sensor 50, and an installation stand 64 provided within the protective tube 62 and holding the water level sensor 50.

As shown in Figures 4 to 6, the protective tube 62 is formed in a bottomed tube shape with a cylindrical side wall 70 and a disk-shaped bottom wall 72, and is erected in the field 100 by embedding the lower end in the field 100. The side wall 70 and bottom wall 72 of the protective tube 62 are formed with a plurality of holes 70a that penetrate in the thickness direction and are distributed throughout the tube wall. The holes 70a are used as inlets and outlets for irrigation water. The diameter of the holes 70a is, for example, 3 mm to 20 mm. Furthermore, the bottom wall 72 is formed with a plurality of insertion holes (not shown) for inserting bolts 82a (described later) arranged at predetermined intervals in the circumferential direction. In addition, a ring-shaped mark line 70b is provided on the outer circumferential surface of the side wall 70. This marked line 70b is set at the same height as the marked line 52b of the water level sensor 50 when it is installed on the installation stand 64, and when the protective tube 62 is erected in the field 100, the height position of this marked line 70b is aligned with the height position of the top surface of the field 100.

The nominal diameter of the protective tube 62 is not particularly limited as long as the housing 52 of the water level sensor 50 can be inserted inside, but is set to, for example, 150 mm to 200 mm. The height dimension (axial length) of the protective tube 62 is set so that the upper end face of the protective tube 62 is at the same height as or slightly higher than the maximum water level of the irrigation water stored in the field 100, and is set to, for example, 350 mm to 450 mm. In this embodiment, the upper end of the water level sensor 50 protrudes above the upper end face of the protective tube 62, but the upper end face of the protective tube 62 may be at the same height as the upper end face of the water level sensor 50 or at a higher height than the upper end face of the water level sensor 50. The axial length of the portion of the protective tube 62 below the mark 70b (the portion buried in the field 100) is set to, for example, 100 mm to 200 mm so that the protective tube 62 can be firmly fixed to the field 100.

Such a protective tube 62 can be formed, for example, by adhesively joining a perforated tube made of synthetic resin such as hard polyvinyl chloride and polyethylene to a short cylindrical cap member with a bottom. However, the perforated tube and the cap member may simply be detachably fitted together. In other words, the side wall 70 may be detachably connected to the bottom wall 72. Furthermore, the size, shape, and material of the protective tube 62 are not particularly limited as long as it can be erected to cover the periphery of the water level sensor 50 and has a certain strength sufficient to withstand strong winds, etc.

The protective tube 62 also has an anchor 74 protruding outward at its lower end. The anchor 74 is provided, for example, by fixing a stainless steel angle bar to the lower end of the outer surface of the protective tube 62 using a fastening member such as a bolt. By providing such an anchor 74 on the protective tube 62, even if the protective tube 62 is erected in a soft field 100, the protective tube 62 can be prevented from floating up and tilting, and the installation accuracy of the protective tube 62 (and thus the water level sensor 50) relative to the field 100 can be improved.

As shown in Figures 4 and 5, the installation base 64 includes a sensor holder 76 that holds the housing 52 of the water level sensor 50, and is attached to the bottom wall 72 of the protective tube 62. In this embodiment, the sensor holder 76 is formed in a short cylindrical shape, and a ring-shaped protruding locking portion 76a is formed at the lower end of the sensor holder 76, protruding inward. The inner diameter of the sensor holder 76 is set to approximately the same size as the outer diameter of the housing 52, for example 48 mm, so that the housing 52 is detachable and the attached housing 52 does not tilt, and the axial length of the portion of the sensor holder 76 above the locking portion 76a is set to, for example, 40 mm to 70 mm, so that the attached housing 52 does not tilt.

The installation base 64 is also formed with a brim-shaped fixing portion 80 that protrudes outward from the lower end of the sensor holding portion 76. This fixing portion 80 is formed with a plurality of insertion holes (not shown) for inserting bolts 82a (described later) arranged at predetermined intervals in the circumferential direction.

When attaching the installation stand 64 to the bottom wall 72 of the protective tube 62, fastening members such as bolts 82a and nuts 82b are used. That is, the installation stand 64 is fixed to the bottom wall 72 of the protective tube 62 by inserting the bolts 82a into insertion holes formed in the bottom wall 72 of the protective tube 62 and the fixing part 80 of the installation stand 64 and tightening them with the nuts 82b. At this time, a cylindrical spacer 84 having a predetermined axial length is fitted onto the bolts 82a. By changing the axial length of this spacer 84, the height position of the sensor holding part 76 can be adjusted. That is, the installation stand 64 is provided so that the height position of the sensor holding part 76 can be adjusted.

The water level sensor 50 is held upright by the installation stand 64, with the lower end of the housing 52 removably fitted into the sensor holding part 76 and the lower end of the housing 52 locked to the locking part 76a. When attaching the installation stand 64 to the protective tube 62, it is advisable to temporarily attach the water level sensor 50 to the sensor holding part 76 and adjust the height of the sensor holding part 76 so that the height of the marked line 52b of the water level sensor 50 coincides with the height of the marked line 70b of the protective tube 62. In this way, after the protective tube 62 with the installation stand 64 attached is erected in the field 100, the installation of the water level sensor 50 can be completed simply by fitting the lower end of the housing 52 into the sensor holding part 76 of the installation stand 64.

In this installation structure 60, the water level sensor 50 is surrounded by the protective tube 62, so waves generated during water supply or strong winds can be prevented from reaching the water level sensor 50 (i.e., water level fluctuations can be mitigated), enabling accurate and stable water level measurement. In addition, the water level sensor 50 is held by the installation base 64, and the protective tube 62 prevents the lower end of the water level sensor 50 from being buried in the soil, preventing erroneous measurements due to soil adhering to the sensor unit 54. In particular, by using the spacer 84 to raise the installation base 64 above the bottom wall 72 of the protective tube 62 (i.e., the lower end of the water level sensor 50 is raised above the lower end of the protective tube 62), even if foreign matter such as mud enters the protective tube 62, the foreign matter will accumulate on the bottom wall 72, reducing adverse effects on the water level sensor 50.

The protective tube 62 and installation stand 64 described above should be permanently installed in the field 100 regardless of the season. On the other hand, the water level sensor 50 should be removed from the field 100 and stored in a storage shed or the like during agricultural off-seasons such as winter. The water level sensor 50 can be removed simply by pulling out the lower end from the sensor holding part 76, making removal easy. Also, once the protective tube 62 and installation stand 64 are firmly installed, the water level sensor 50 can be accurately installed in the same position simply by fitting the lower end of the housing 52 into the sensor holding part 76. In other words, the removal and installation of the water level sensor 50 can be easily performed, and the installation accuracy of the water level sensor 50 in the field 100 can be improved.

When the side wall 70 of the protective tube 62 is detachably connected to the bottom wall 72, the side wall 70 of the protective tube 62 can also be removed from the field 100 and stored in a storage shed during agricultural off-seasons such as winter. In addition, when foreign matter accumulates on the bottom wall 72, the foreign matter on the bottom wall 72 can be easily removed by removing the side wall 70.

As described above, according to this embodiment, the water level sensor 50 is surrounded by the protective tube 62, so that the water level sensor 50 is less susceptible to the effects of waves that occur during water supply or strong winds, and the readings of the sensor unit 54 are stable. Furthermore, by surrounding the water level sensor 50 with the protective tube 62 and supporting it with the installation base 64, the water level sensor 50 is prevented from being buried in the soil, and erroneous measurements due to soil adhering to the sensor unit 54 can be prevented. Therefore, the detection accuracy of the water level sensor 50 can be improved.

In the above embodiment, a perforated pipe with multiple holes 70a distributed on the pipe wall was used as the side wall 70 of the protective pipe 62, but the shape, size, formation position and number of the holes 70a can be changed as appropriate. For example, the side wall 70 of the protective pipe 62 can be formed from a Netron (registered trademark) pipe with a mesh structure in which countless holes are formed on the pipe wall.

As shown in the embodiment in FIG. 7, a mud filter 90 can be provided on the inner surface of the protective tube 62. The mud filter 90 has numerous small holes smaller than the holes 70a of the protective tube 62, and is formed, for example, in a cylindrical shape so as to cover the inner surface of the side wall 70. The mud filter 90 can be made of a nonwoven fabric made of synthetic resin.

In this way, by providing the mud shielding filter 90 on the inner peripheral surface of the side wall 70 of the protective tube 62, it is possible to prevent mud from entering the protective tube 62 through the hole 70a of the side wall 70, and therefore to prevent erroneous measurements due to mud adhering to the sensor portion 54 of the water level sensor 50. This further improves the detection accuracy of the water level sensor 50. In addition, if the mud shielding filter 90 is made detachable from the side wall 70 of the protective tube 62, when the mud shielding filter 90 becomes clogged, for example, it can be removed from the protective tube 62 and washed, allowing the mud shielding filter 90 to be used repeatedly.

In FIG. 7, the water level sensor 50 is omitted for ease of understanding. The same reference numbers are used for parts common to the above-mentioned embodiment, and duplicated descriptions are omitted or simplified. The same omission of duplicated descriptions applies to the other embodiments described below.

In the above embodiment, the lower end of the water level sensor 50 is only held by the installation base 64, but as in the embodiment shown in FIG. 8, a positioning member 92 can be further provided. The positioning member 92 is a member for restricting the lateral movement of the housing 52 of the water level sensor 50 to prevent the housing 52 from shifting laterally relative to the protective tube 62, and is provided to connect the upper end of the side wall 70 of the protective tube 62 to the upper end of the housing 52 of the water level sensor 50. For example, the positioning member 92 includes a ring-shaped holding portion 92a that is fitted to the upper end of the housing 52, and a connecting portion 92b that connects the holding portion 92a to the upper end of the side wall 70 of the protective tube 62. The end of the connecting portion 92b on the protective tube 62 side is fixed to the upper end of the side wall 70. The inner diameter of the holding portion 92a is preferably set to be approximately the same as the outer diameter of the housing 52 so that the housing 52 can be attached and detached in the axial direction. This makes it easy to remove and install the water level sensor 50 by simply inserting and removing the water level sensor 50 from above the positioning member 92 into the holding portion 92a and the sensor holding portion 76 of the installation base 64.

In this way, by providing a positioning member 92 that connects the upper end of the protective tube 62 to the upper end of the water level sensor 50 and restricts the lateral movement of the water level sensor 50, lateral shift (tilt) of the upper end of the water level sensor 50 is reliably prevented even in strong winds, thereby further improving the installation accuracy and detection accuracy of the water level sensor 50.

Although not shown, the holding portion 92a of the positioning member 92 can be formed to be contractible (tightenable). For example, a notch can be formed in a portion of the circumference of the holding portion 92a, and the holding portion 92a can be contracted by tightening the tightening portion. This allows the holding portion 92a to tighten the housing 52, firmly bringing the inner surface of the holding portion 92a into close contact with the outer surface of the housing 52, so that the positioning member 92 can also restrict the vertical movement of the water level sensor 50. Therefore, the water level sensor 50 can be properly positioned in the vertical direction (especially to prevent it from coming loose), and the installation accuracy and detection accuracy of the water level sensor 50 can be further improved.

Furthermore, as in the embodiment shown in Figure 8, a cover 94 can be provided to cover the upper opening of the protective tube 62. The cover 94 is formed, for example, in a tapered shape that slopes downward from the center to the periphery (i.e., the diameter decreases as it goes upward), and is placed on the protective tube 62. In this embodiment, since the upper end of the water level sensor 50 protrudes above the upper end surface of the protective tube 62, an opening is formed in the center of the cover 94 through which the water level sensor 50 is inserted.

In this way, by providing a cover 94 that covers the upper opening of the protective tube 62, foreign matter such as grass pieces and soil scattered during weeding and plowing is prevented from entering the protective tube 62. This prevents erroneous measurements caused by foreign matter such as grass pieces and soil adhering to the sensor portion 54 of the water level sensor 50, and further improves the detection accuracy of the water level sensor 50. In addition, by forming the connecting portion 92b of the positioning member 92 into a circular plate shape, the positioning member 92 (connecting portion 92b) can also be used as a cover.

In the above embodiment, the installation base 64 that holds the lower end of the housing 52 of the water level sensor 50 is exemplified as an example of the installation base, but the form of the installation base is not limited to this. For example, as in the embodiment shown in FIG. 9, an installation base 96 that holds the upper end of the housing 52 can be used. Simply put, the installation base 96 has a ring-shaped sensor holding portion 96a that is fitted onto the upper end of the housing 52. The sensor holding portion 96a has a notch in a part of the circumferential direction, and can be reduced in diameter by tightening the tightening portion 96b. The installation base 96 also has a connecting portion 96c that connects the sensor holding portion 96a and the upper end of the side wall 70 of the protective tube 62, and the end of this connecting portion 96c on the protective tube 62 side is fixed to the upper end of the side wall 70. Then, the upper end of the housing 52 of the water level sensor 50 is fitted into the sensor holding portion 96a, and the sensor holding portion 96a is clamped to the upper end of the housing 52, so that the inner surface of the sensor holding portion 96a and the outer surface of the housing 52 are tightly attached to each other, and the water level sensor 50 is held upright by the installation base 96.

In the embodiment shown in FIG. 9, as in the above-described embodiment, the water level sensor 50 is surrounded by a protective tube 62 and held by an installation base 96, so that the water level sensor 50 is less susceptible to the effects of waves that occur during water supply or strong winds. In addition, the water level sensor 50 is prevented from being buried in the soil, so erroneous measurements caused by soil adhering to the sensor unit 54 are prevented. This improves the detection accuracy of the water level sensor 50.

In the embodiment shown in FIG. 9, the water level sensor 50 is held by fastening the upper end of the housing 52 with the sensor holding portion 96a, but the water level sensor 50 can also be held by providing a protrusion (stopper) on the outer surface of the housing 52 and engaging this protrusion with the upper end of the sensor holding portion 96a. Also, by forming the connecting portion 96c of the installation base 96 into a circular plate shape, the installation base 96 (connecting portion 96c) can also be used as a cover that covers the upper opening of the protective tube 62.

In addition, in the above-described embodiment, the installation structure 60 is provided within the cultivated area of the field 100 divided by the ridges 102, but this is not limited to the above. Although not shown, it is also possible to provide a field extension section on the ridges 102 that is connected to the cultivated area of the field 100 by excavating the ridges 102, and provide the installation structure 60 in this field extension section.

By providing the installation structure 60 in the field expansion section, the water level sensor 50 is less susceptible to the effects of water level fluctuations during water supply, and the detection accuracy of the water level sensor 50 can be improved. In addition, because the installation state of the protective tube 62 and the installation bases 64, 96 is stable, the water level sensor 50 can be installed more accurately in the same position even if it is removed and reinstalled during the agricultural off-season, etc. In other words, the installation accuracy of the water level sensor 50 can be improved, and in turn the detection accuracy of the water level sensor 50 can be improved. Furthermore, because the installation structure 60 does not extend into the cultivated area of the field 100, it is less likely to interfere with agricultural work.

Furthermore, in the above embodiment, the installation base 64 is fixed to the bottom wall 72 of the protective tube 62, but the installation base 64 can also be installed independently (separately) from the protective tube 62. For example, when the installation structure 60 is provided in the field expansion section, the field expansion section can be formed of concrete or the like. It is preferable to fix the installation base 64 to the concrete that forms the field expansion section without providing the bottom wall 72 to the protective tube 62. By separating the protective tube 62 and the installation base 64, even if an agricultural machine or the like hits the protective tube 62 and causes the protective tube 62 to tilt slightly, the installation base 64 and the water level sensor 50 can be prevented from being affected.

Note that the specific values and shapes of the dimensions given above are merely examples and can be changed as necessary depending on the product specifications, etc.

REFERENCE SIGNS LIST 10 Field water management system 12 Water supply tap 14 Water outlet 16 Electric actuator 50 Water level sensor 52 Housing 54 Sensor unit 60 Water level sensor installation structure 62 Protective tube 64, 96 Installation stand 76 Sensor holder 90 Mud-blocking filter 92 Positioning member 94 Cover 100 Field

Claims (10)

A water level sensor installation structure for detecting a water level in a farm field,
A water level sensor including a sensor unit that detects a water level in a field by utilizing a change in capacitance or pressure of the field water , and a vertical cylindrical housing that houses the sensor unit;
A water level sensor installation structure comprising: a protective cylinder having a plurality of holes penetrating in the thickness direction, the lower end of which is embedded in the field so as to surround the housing, and an installation base having a sensor holding part that holds the housing. The water level sensor installation structure according to claim 1, wherein the lower end of the housing is removably fitted into the sensor holding portion. The protective cylinder is formed into a bottomed cylinder having a side wall and a bottom wall,
3. The water level sensor installation structure according to claim 2, wherein the installation base is attached to the bottom wall. The water level sensor installation structure according to claim 2 or 3, wherein the installation base is provided so that the height position of the sensor holding part can be adjusted. The water level sensor installation structure according to any one of claims 2 to 4, further comprising a positioning member that is provided to connect the upper end of the protective tube with the upper end of the housing and prevents the housing from shifting sideways relative to the protective tube. The water level sensor installation structure according to claim 1, wherein the installation base has the sensor holding part that holds the upper end of the housing, and a connecting part that connects the sensor holding part to the upper end of the protective tube. The water level sensor installation structure according to any one of claims 1 to 6, further comprising a mud filter provided on the inner surface side of the protective tube to prevent mud from entering the protective tube through the multiple holes. The water level sensor installation structure according to any one of claims 1 to 7, further comprising an anchor protruding outward from the protective tube. The water level sensor installation structure according to any one of claims 1 to 8, further comprising a cover that covers the upper opening of the protective tube. The field includes a field extension portion provided on a ridge that divides the field,
The water level sensor installation structure according to any one of claims 1 to 9, wherein the water level sensor installation structure is provided in the farm field expansion section.

Images