JP2008237135A - Underground irrigation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an underground irrigation system preventing a water-supply pipe from causing siphon effect. <P>SOLUTION: The underground irrigation system is provided with a water-supply pipe 12 and a laying pipe laid in a cultivated field: wherein the water-supply pipe 12 is provided with an air hole 40 and receiving holes 44 at a part upper than an underground water level W in the cultivated field, projections 48 of an air suction valve 42 are fitted to the receiving holes 44 to fix the air suction valve 42 to a position upper than the air hole 40, and a valve part 46 of the air suction valve 42 blocks up the air holes 40. Such a structure results in that the valve part 46 turns up due to difference in barometric pressure and the air hole 40 opens so as to take in the open air through the air hole 40 when the water-supply pipe is evacuated, so that the water-supply pipe 12 is prevented from causing siphon effect. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an underground irrigation system, and more particularly to an underground irrigation system that adjusts the groundwater level of a cultivated land by supplying irrigation water with a laying pipe or discharging the groundwater.

An example of a conventional underground irrigation system is disclosed in Patent Document 1. In the float valve of Patent Document 1, a water supply pipe is connected to a water storage tank, and a valve main body is attached to the tip of the water supply pipe, and a valve body in the valve main body and a float floating in the water storage tank are connected by an interlocking mechanism. Has been. By this interlocking mechanism, when the float moves up and down according to the fluctuation of the water level in the water storage tank, the valve element opens and closes the water supply pipe in conjunction with the up and down movement.
Japanese Patent No. 3026421 [F16K 31/24, E03B 11/00, F16H 21/10]

  When the pump connected to the water supply pipe is stopped, or when the flow velocity of the water flowing through the main body of the branched water supply pipe suddenly increases, the inside of the water supply pipe may become negative pressure. In such a case, in the prior art of Patent Document 1, since the tip opening of the water supply pipe is immersed in the water in the water storage tank, the water supply pipe sucks up the water in the water storage tank due to negative pressure.

  Therefore, the main object of the present invention is to provide an underground irrigation system that prevents siphons in water pipes.

  The invention of claim 1 includes a water supply pipe, a laying pipe that is laid on the cultivated land, and supplies the irrigated water supplied from the water supply pipe to the cultivated land, and siphon prevention means that sucks outside air into the water supply pipe to prevent siphon. Underground irrigation system.

  In the invention of claim 1, a laying pipe (14: reference numeral exemplifying a corresponding part in the embodiment; the same applies hereinafter) is laid on the cultivated land (18). Water is supplied to the laying pipe from the water supply pipe (12), and the water is supplied to the cultivated land through the laying pipe. In such an underground irrigation system (10), for example, when the pressure in the water supply pipe becomes negative, the siphon prevention means (42, 88, 92, 112, 122) sucks outside air into the water supply pipe, thereby The atmospheric pressure increases. As a result, the negative pressure reduces the force of the water supply pipe to suck up irrigation water, groundwater in the cultivated land, and the like, and siphoning of the water supply pipe can be prevented.

  The invention of claim 2 is characterized in that the siphon prevention means includes an intake valve that closes an air hole provided in the water supply pipe above the groundwater level of the cultivated land and opens the air hole by a negative pressure in the water supply pipe. The described underground irrigation system.

  In the invention of claim 2, for example, when a water supply pipe is inserted in a water tank or the like connected to the laying pipe, the water level of the water tank becomes equal to the groundwater level of the cultivated land, but water is supplied above the groundwater level of the cultivated land. If an air hole (40) is provided in a pipe | tube, since an air hole is located above the water surface of a water tank, the inside of a water supply pipe and external air will be connected by an air hole. An intake valve (42, 92, 112, 122) is attached to such an air hole, and the intake valve opens the air hole at the time of negative pressure in the water supply pipe. For this reason, even if negative pressure is generated in the water supply pipe, the intake valve opens the air hole, so that outside air is sucked into the water supply pipe through the air hole, and siphoning of the water supply pipe can be prevented.

  The invention of claim 3 further includes a water level manager provided in the water supply pipe, and the water level manager is connected to the float linked to the groundwater level of the cultivated land with the water pipe as a guide, and the float rises. 3. The underground irrigation system according to claim 2, further comprising a valve body that closes the water supply port of the water supply pipe and opens the water supply port of the water supply pipe when the float descends, and the intake valve is disposed above the float.

  In the invention of claim 3, the water level management device (36) is provided in the water supply pipe, and is accommodated in, for example, a water tank connected to the laying pipe. Since the water level of this aquarium substantially matches the groundwater level, and the float (38) floats on the water surface of the aquarium and is linked to the groundwater level of the cultivated land, it is covered with the atmosphere above the float that floats on the water surface. Therefore, since the intake valve located above the float is placed in the atmosphere, even in an underground irrigation system equipped with a water level controller, outside air is drawn into the water supply pipe through the intake valve when the pressure in the water supply pipe becomes negative. In addition, siphoning of the water supply pipe can be prevented.

  Note that “above the float” means above the groundwater level when the float is floating, and indicates a position above the design height of the groundwater level.

  The invention according to claim 4 is the underground irrigation according to claim 2 or 3, wherein the intake valve is formed of an elastic material, is disposed on the inner surface of the water supply pipe, is fixed above the air hole, and opens the air hole by elastic deformation. System.

  In the invention of claim 4, when the intake valve (42, 112) is made of an elastic material and is fixed above the air hole on the inner surface of the water supply pipe, the intake valve is elastically deformed by the negative pressure and turned up. Since the air hole is opened, siphoning of the water supply pipe can be prevented. Further, the shape of the intake valve is simple, and the intake valve can be easily fixed, so that it is excellent in workability and economy.

  The invention of claim 5 is a water level controller provided in a water supply pipe for supplying water, and is connected to a float linked to the groundwater level of the cultivated land using the water supply pipe as a guide, and when the float rises, the water supply pipe A water level controller comprising: a valve body that closes the water supply opening of the water supply pipe and opens the water supply opening of the water supply pipe when the float descends; and a siphon prevention means that is provided above the float and sucks outside air into the water supply pipe to prevent siphon. It is.

  In the invention of claim 5, for example, the water level manager is accommodated in a water tank connected to the laying pipe, and the water level of the water tank substantially coincides with the groundwater level. As a result, the float floats on the surface of the aquarium and is linked to the groundwater level of the cultivated land, and the intake valve above the float is in the atmosphere, so if negative pressure occurs in the water supply pipe, outside air is drawn into the water supply pipe through the intake valve. Inhalation can prevent siphoning of water pipes.

  Note that “above the float” means above the groundwater level when the float is floating, and indicates a position above the design height of the groundwater level.

  According to the present invention, the siphon of the water supply pipe can be prevented by providing the water supply pipe with the siphon prevention means for sucking outside air.

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

  As shown in FIGS. 1 to 4, the underground irrigation system 10 according to an embodiment of the present invention shown in FIG. 1 includes a water supply pipe 12, a laying pipe 14, a drainage channel 16, and siphon prevention means. It is used to adjust the groundwater level of the cultivated land 18 by supplying water to the cultivated land 18 and discharging the groundwater of the cultivated land 18 to the drainage channel 16.

  The water supply pipe 12 is a pipe that supplies and supplies water to the laying pipe 14, and includes a main pipe 20 and a branch pipe 22 that branches from the main pipe 20, and the branch pipe 22 includes a main body portion 24 and a tip end portion 26. For the main body 24, for example, a pipe line connecting a plurality of straight tubes or flexible tubes, or a single flexible tube is used. The distal end portion 26 is a straight pipe and is formed of, for example, a metal such as SUS or a synthetic resin such as vinyl chloride resin. One end portion of the distal end portion 26 is a connection portion for connecting to the main body portion 24, and the other end is used as a valve seat 30 that receives the valve body 28, and the other end opening supplies water into the water tank 32. It is used as the water supply port 34. The water supply pipe 12 is provided with siphon prevention means and a water level manager 36.

  The siphon prevention means is a means for preventing siphon that the water supply pipe 12 sucks up water when the inside of the water supply pipe 12 becomes negative pressure, and is above the ground water level W of the float 38 and the cultivated land 18, that is, in the atmosphere. And disposed in the water supply pipe 12. The position of the siphon prevention means is not particularly limited, and may be either a horizontally piped part or a vertically piped part of the water supply pipe 12, or any of the main body part 24 and the tip part 26. A portion as close as possible to the distal end portion 26, particularly the water supply port 34, is preferable. This is because if the portion close to the water supply port 34 is quickly opened to the atmosphere, the intrusion of water flowing back from the water supply port 34 can be prevented. Further, the siphon prevention means includes an air hole 40 and an intake valve 42 shown in FIGS.

  The air hole 40 is a hole opened in the water supply pipe 12 in order to draw outside air into the water supply pipe 12, and penetrates the pipe wall of the water supply pipe 12. For example, three through holes are provided in the water supply pipe 12 at intervals in the axial direction, and the upper two through holes are used as receiving holes 44 for fixing the intake valve 42 and the remaining lower one The two through holes are used as air holes 40.

  The intake valve 42 normally closes the air hole 40 and opens the air hole 40 at the time of negative pressure in the water supply pipe 12. The intake valve 42 is disposed inside the water supply pipe 12 and is fixed above the air hole 40. , Formed of an elastic material or the like, and includes a valve portion 46 and a protrusion 48. The valve portion 46 is located on the inner surface of the water supply pipe 12, and the valve portion 46 is a rectangular flat plate and includes, for example, two protrusions 48. The width of the valve part 46 is larger than the diameter of the air hole 40, and the length of the valve part 46 is set to a length that covers the two receiving holes 44 and the air hole 40. The protrusion 48 fits into the receiving hole 44 and is used to fix the intake valve 42 to the water supply pipe 12, and is disposed on the upper portion of the intake valve 42. The diameter of the protrusion 48 is set to a size that fits into the receiving hole 44 and does not come out of the receiving hole 44, and the length of the protrusion 48 is set to be the same as or substantially the same as the thickness of the pipe wall of the water supply pipe 12.

  As a result, when the protrusions 48 are inserted into the two upper receiving holes 44 and the intake valve 42 is fixed to the water supply pipe 12, the lower part of the valve part 46 extends downward in the vertical direction and closes the air hole 40. And the lower part of the valve part 46 is elastically deformed by the pressure difference etc. at the time of the negative pressure in the water supply pipe 12, and opens the air hole 40. FIG.

  As shown in FIGS. 2 to 3 and FIGS. 9 to 11, the water level manager 36 is accommodated in the water tank 32 and adjusts the supply of water according to the water level in the water tank 32. The shaft fixing tool 50 and the float 38 are disposed around the branch pipe 22.

  The water tank 32 is a water storage part such as an artificial water tank, a pit such as a pipe and a well, and a reservoir. For example, a part where the laying pipe 14 is raised, that is, a vertical pipe part is used as the water tank.

  The shaft fixing tool 50 is attached to the branch pipe 22 and has an end portion that prevents the branch pipe 22 from tilting along the inner surface of the water tank 32, and is formed of, for example, a flat plate. The shaft fixture 50 is made of a synthetic resin such as polyvinyl chloride, and includes an insertion hole 52 shown in FIG. The insertion hole 52 is a hole through which the branch pipe 22 is inserted, and is arranged at the center or substantially the center of the shaft fixture 50. Then, the shaft fixing tool 50 is fixed to the branch pipe 22 passed through the insertion hole 52 with a screw or the like. Further, the end of the shaft fixing tool 50 is formed in an arc shape or the like so that the end of the shaft fixing tool 50 is along the inner surface of the water tank 32, and the length of the shaft fixing tool 50 is set slightly smaller than the inner diameter of the water tank 32. Further, the two shaft fixtures 50 are respectively attached to the upper part and the lower part of the branch pipe 22, and these are arranged so as to intersect at right angles to each other. The upper shaft fixture 50 includes a length adjusting unit 54. The length adjusting unit 54 finely adjusts the length of the shaft fixture 50, and a bolt or the like is used. The length adjusting portion 54 is attached toward the side surface of the upper shaft fixing tool 50, and the length adjusting portion 54 is rotated to change the length protruding from the side surface of the shaft fixing device 50, thereby changing the shaft fixing tool 50. The length of is adjusted.

  The float 38 is disposed above the water supply port 34, floats on the water surface in the water tank 32, and moves up and down according to fluctuations in the water level in the water tank 32, and uses a synthetic resin such as vinyl chloride, polypropylene, or polyethylene. And formed by hollow molding or the like. This synthetic resin is appropriately selected. The float 38 has, for example, a ring shape and includes a through hole 56 at the center thereof. In order to prevent the float 38 from contacting the inner surface of the water tank 32, the diameter of the float 38 is set smaller than the inner diameter of the water tank 32. The height of the float 38 is set according to the required buoyancy of the float 38, that is, the force with which the valve body closes the water supply port 34.

  The through hole 56 is a portion through which the branch pipe 22, particularly the distal end portion 26 passes, and penetrates the float 38 in the axial direction. The diameter of the through hole 56 is set to be slightly larger than the outer diameter of the branch pipe 22 so that the float 38 can move along the branch pipe 22.

  The float 38 further includes two float link portions 58. The float link portion 58 is formed of a plate-like body made of a synthetic resin such as vinyl chloride, polypropylene, or polyethylene. The two float link portions 58 are joined to the lower surface of the float 38 by welding or the like with the through hole 56 interposed therebetween. A link mechanism 60 is joined to the float link portion 58, and the float 38 is connected to the valve body 28 via the link mechanism 60.

  As shown in FIGS. 9 to 11, the valve body 28 is disposed below the water supply port 34, contacts the valve seat 30 and closes the water supply port 34, and when the float 38 rises, the water supply port 34. And when the float 38 descends, the water supply port 34 is opened to adjust the amount of water supplied from the water supply port 34. The valve body 28 includes a contact part 63 a, a seat part 63 b, an angle adjustment part 64, and a valve body link part 62. The contact portion 63a has a disk shape and includes a contact surface 63c on the surface thereof. The contact portion 63a is formed of an elastic material such as ethylene propylene rubber, or a synthetic resin so that the contact surface 63c contacts the valve seat 30 without a gap. The contact surface 63 c is a flat surface that contacts the valve seat 30 and closes the water supply port 34, faces the water supply port 34, and is disposed in parallel to the valve seat 30. The seat portion 63b is a portion that supports the contact portion 63a, is formed in a disc shape using a synthetic resin such as vinyl chloride resin or a metal such as SUS, and the contact portion 63a and the back surface of the contact portion 63a. Arranged in layers. The diameters of the abutting portion 63a and the seat portion 63b are large enough to hit the valve seat 30, and are set larger than the diameter of the valve seat 30, that is, the outer diameter of the tip of the branch pipe 22. Further, the valve element 28 is connected to the valve element link part 62 via the angle adjusting part 64.

  The angle adjusting portion 64 is disposed between the seat portion 63b and the valve body link portion 62 so as to support the contact portion 63a and the seat portion 63b and adjust the angle of the contact surface 63c by elastic deformation or the like. The abutting portion 63a and the seat portion 63b are fixed to the valve body link portion 62 with bolts or the like. The angle adjusting unit 64 is formed in a disk shape or a cylindrical shape using an elastic material such as ethylene propylene rubber or a synthetic resin. The diameter of the angle adjusting unit 64 is set smaller than the diameters of the contact part 63a and the seat part 63b because the contact part 63a and the seat part 63b are inclined. If the hardness of the angle adjusting portion 64 is too small, the force that the angle adjusting portion 64 supports the contact portion 63a and the seat portion 63b becomes weak, and the contact surface 63c cannot contact the valve seat 30 without a gap. On the other hand, if the angle is too large, the angle adjusting portion 64 is difficult to be deformed, so that the angle of the contact surface 63c cannot be adjusted appropriately due to elastic deformation. Is done.

  The valve body link part 62 is connected to the link mechanism 60 while supporting the contact part 63a, the seat part 63b, and the angle adjustment part 64, and is U-shaped using a metal such as SUS or a synthetic resin. It is formed in a shape. Both ends of the valve body link part 62 are connected to the link mechanism 60, and a contact part 63 a, a seat part 63 b and an angle adjustment part 64 are attached to the center of the valve body link part 62.

  The link mechanism 60 transmits the movement of the float 38 to the valve body 28, and links the vertical movement of the float 38 and the movement of the valve body 28 opening and closing the water supply port 34. 70 and third section 72. The link mechanism 60 includes two first arms 74, two second arms 76, and two third arms 78. The first arm 74, the second arm 76, and the third arm 78 are each made of SUS or the like. It is formed of a flat bar using a metal or a synthetic resin. A first node 68 is provided on the first arm 74, a second node 70 is provided on the second arm 76, and a third node 72 is provided on the third arm 78. The length between the first node 68 and the second node 70 is set longer than the length between the second node 70 and the third node 72. Also, the two first arms 74 are pin-joined at the respective upper ends, and the lower ends of the first nodes 68 are pin-joined with the upper ends of the second arms 76, and the two second arms 76 intersect each other. The lower ends of the second arms 76 are pin-joined with the upper ends of the third arms 78, and the lower ends of the two third arms 78 are pin-joined. Thereby, two rhombus portions are provided, and the upper rhombus portion is formed larger than the lower rhombus portion. In addition, since each arm 68, 70, 72 is rotatably joined by pin joining, each rhombus can be deformed, as shown in FIGS. 9 and 11, The length of the diagonal line of the diamond shape expands and contracts.

  The first joint 68 is a connection joint with the float 38 to which the float 38 is pin-joined via the float link portion 58. The second node 70 is a connection node with the valve body 28 to which the contact portion 63a and the like are pin-joined via the valve body link portion 62. The third node 72 is a connection node with the branch tube 22 to which the branch tube 22 is pin-jointed together with the shaft fixture 50.

  Thus, the two link mechanisms 60 are arranged with the branch pipe 22 and the valve body 28 interposed therebetween, and are connected to the float 38, the branch pipe 22 and the valve body 28. Then, as shown in FIG. 9, when the float 38 is lowered along the branch pipe 22, the valve body 28 is lowered accordingly, and the valve body 28 opens the water supply port 34. On the contrary, as shown in FIG. 11, when the float 38 rises along the branch pipe 22, the valve body 28 rises accordingly, and the valve body 28 closes the water supply port 34.

  As shown in FIGS. 4 and 10, the water level manager 36 includes a finger pinching prevention cover 80, and the finger pinching prevention cover 80 is attached to the front surface of the link mechanism 60. The finger pinching prevention cover 80 is a cover that prevents a finger from being pinched by the link mechanism 60 when the finger enters the rhombus and the link mechanism 60 expands and contracts. The finger pinching prevention cover 80 is formed of ethylene propylene rubber or the like, and its size is set to a size that covers the link mechanism 60, particularly the rhombus.

  Then, the water level manager 36 connects the main body portion 24 to the distal end portion 26 and sets the float 38 so as to be positioned at a predetermined water level setting value in a state where the valve body 28 is in contact with the valve seat 30. By adjusting the length adjusting unit 54 and fixing the water supply pipe 12 to the water tank 32, it is installed in the water tank 32.

  A drainage channel 16 shown in FIG. 2 is a water channel for discharging excess groundwater in the cultivated land 18, and is connected to a water level setting device 82.

  The water level setter 82 sets the groundwater level W of the cultivated land 18 and includes an outer pipe portion 84 and an inner pipe portion 86. The outer tube portion 84 is arranged in the vertical direction, has a bottom at its lower end, opens at its upper end, and is attached to the upper end opening so that a lid can be opened and closed. The upper end opening is used as an inspection port of the underground irrigation system 10 by opening the lid. The drainage channel 16 is connected to the downstream side surface of the outer tube portion 84, and the inner tube portion 86 is disposed in the outer tube portion 84.

  The inner pipe portion 86 is arranged in the vertical direction, both ends are open, and the lower end opening is connected to the laying pipe 14 via a joint or the like. The height of the inner pipe portion 86 is set so that the upper end thereof is positioned at the groundwater level set value S of the cultivated land 18.

  The laying pipe 14 is a perforated pipe that supplies water from the water supply pipe 12 to the cultivated land 18 and discharges groundwater from the cultivated land 18. The laying pipe 14 includes a large number of pores, is laid on the cultivated land 18, and a plurality of laying pipes 14 are connected between the water tank 32 and the water level setting device 82. Thereby, the laying pipe 14 interlocks the water level of the water tank 32 and the water level of the water level setting device 82 with the groundwater level W of the cultivated land 18.

  In such an underground irrigation system 10, as shown in FIG. 2, when the groundwater level W of the cultivated land 18 is lower than the groundwater level set value S, the water level of the aquarium 32 becomes the same height as the groundwater level W, and the float 38 Falls below the groundwater level set value S, and accordingly, the link mechanism 60 contracts, the valve body 28 descends, and the water supply port 34 opens. Water is supplied from the water supply port 34 to the water tank 32, and the water is supplied to the cultivated land 18 from the many pores of the laying pipe 14 through the laying pipe 14.

  On the other hand, as shown in FIG. 3, when the groundwater level W of the cultivated land 18 is the same as or higher than the groundwater level set value S, the water level of the water tank 32 is the same as the groundwater level set value S in conjunction with the groundwater level W or Accordingly, the float 38 is equal to or higher than the groundwater level set value S. When the float 38 rises, the link mechanism 60 extends to raise the valve body 28, the valve body 28 hits the valve seat 30, closes the water supply port 34, and the supply of water is stopped.

  In addition, when the groundwater level W of the cultivated land 18 is higher than the groundwater level set value S, the groundwater of the cultivated land 18 flows into the laying pipe 14, flows through the laying pipe 14 to the inner pipe portion 86, and It overflows from the upper end opening to the outer pipe portion 84 and is discharged from the outer pipe portion 84 to the drainage channel 78 through the drainage channel 16.

  When the inside of the water supply pipe 12 becomes negative pressure in the underground irrigation system 10, the lower part of the intake valve 42 is elastically deformed by the pressure difference between the inside and outside of the water supply pipe 12, and the air hole 40 is opened. As a result, outside air is sucked into the water supply pipe 12, and the air pressure in the water supply pipe 12 rises. As a result, the negative pressure reduces the force of the water supply pipe 12 trying to suck up water for use, the ground water of the cultivated land 18 and the like, and siphoning of the water supply pipe 12 is prevented.

  Moreover, if the water flows back through the water supply pipe 12 due to not only the pressure difference but also the negative pressure, the intake valve 42 is elastically deformed and turned up by the water pressure flowing back, the air hole 40 is opened, and the siphon of the water supply pipe 12 opens. Is prevented.

  Further, in the water tank 32 connected to the laying pipe 14, dirt such as mud and soil is mixed in the water in the water tank 32, but when siphon is prevented, the dust does not enter the water supply pipe 12, and the water supply pipe Inconveniences such as a valve provided at 12 are prevented.

  In particular, when the air hole 40 is provided in the branch pipe 22 above the groundwater level of the cultivated land 18 and the float 38, the air hole 40 and the intake valve 42 are disposed above the water surface of the water tank 32, that is, in the atmosphere. For this reason, if the intake valve 42 opens the air hole 40 when the inside of the water supply pipe 12 becomes negative pressure, the air hole 40 connects the inside of the branch pipe 22 and the outside air, so that the intake valve 42 can be surely passed through. Outside air can be sucked into the branch pipe 22 and siphoning of the water supply pipe 12 can be prevented.

  The shape of the intake valve 42 is simple, and the intake valve 42 can be easily fixed simply by fitting the projection 48 into the receiving hole 44. Therefore, the workability and economy are excellent.

  The siphon prevention means is not limited to the intake valve 42 and the air hole 40 in FIG. 5 as long as it prevents the water supply pipe 12 from sucking up water or the like when the pressure in the water supply pipe 12 becomes negative. A conventional intake valve or the like can be used, or a conventional check valve can be used instead of the intake valve.

  Moreover, the intake pipe 88 shown in FIG. 12 can also be used as a siphon prevention means. The intake pipe 88 is a narrow pipe having a bent shape, and is disposed above the water supply pipe 12. An air hole 40 is provided at the top of the branch pipe 22, and a base end of the intake pipe 88 is connected thereto, and the intake pipe 88 rises therefrom. The intake pipe 88 is disposed above the water supply pipe 12 and extends upward from the water supply pipe 12 so that the water flowing through the water supply pipe 12 flows into the intake pipe 88 and does not leak from the opening at the tip of the intake pipe 88. When the pressure in the pipe 12 becomes negative, outside air is taken into the water supply pipe 12 from the opening of the intake pipe 88 and the air hole 40, so that siphoning of the water supply pipe 12 can be prevented. In addition, although the tip of this intake pipe 88 is bent, it does not need to be bent.

  As another siphon prevention means, an intake valve 92 shown in FIG. 13 can be used. The intake valve 92 includes a lid portion 94 and a valve portion 96, and the lid portion 94 includes a cylindrical side surface 98, an upper surface 100 provided at one end of the side surface 98, and a flange 102 provided at the other end. The inner diameter of the side surface 98 is set larger than the diameter of the air hole 40 provided in the water supply pipe 12. The upper surface 100 includes a through-hole 104, and the ridge 102 extends radially outward from the other end of the side surface 98. The valve portion 96 is connected to the shaft portion 106, is formed in a disk shape larger than the diameter of the air hole 40, and has a plurality of vent holes 108 penetrating in the axial direction. The shaft portion 106 has a hollow cylindrical shape, and has an end ventilation hole 110a and a plurality of side ventilation holes 110b. The shaft portion 106 is passed through the through hole 104, and the valve portion 96 is disposed so as to face the air hole 40. Such an intake valve 92 is fixed by bolts or the like with the flange 102 applied to the outer surface of the water supply pipe 12, and when the valve portion 96 hits the upper surface 100, the valve portion 96 closes the side vent hole 110b, while the valve portion When 96 is on the air hole 40 side, the end air hole 110a, the inside of the shaft portion 106, and the side air hole 110b communicate with each other, and the air hole 40 is opened. When water is flowing through the water supply pipe 12, the valve portion 96 is pressed against the upper surface 100 by the water pressure of the water, and the side vent hole 110 b is closed. On the other hand, when negative pressure is generated in the water supply pipe 12. The valve portion 96 moves to the air hole 40 side due to the pressure difference, opens the air hole 40, opens the water supply pipe 12 to the atmosphere, and siphon is prevented.

  Moreover, the intake valve 112 shown in FIG. 14 can also be used for a siphon prevention means. The intake valve 112 is formed of an elastic material, has a locking portion 114 and a valve portion 116, and a fixture 118 is used for this fixing. The locking portion 114 includes a portion 114 a along the inner surface of the receiving hole 120 and a portion 114 b along the outer surface of the water supply pipe 12, and the valve portion 116 is formed of a rectangular plate-like body and is formed on the inner surface of the water supply pipe 12. Be placed. The fixing tool 118 is used for fixing the intake valve 112 and water-stopping the air hole 40, and is formed of an elastic material that can be deformed and has water-stopping properties, and includes a head. When using this intake valve 112, for example, the receiving hole 120 and the air hole 40 are opened in the water supply pipe 12, the locking portion 114 is inserted into the receiving hole 120 from the outside of the water supply pipe 12, and hung on the edge of the receiving hole 120. Then, a fixing tool 118 is inserted into the upper receiving hole 120 from the outside of the water supply pipe 12 to fix the intake valve 112 to the water supply pipe 12. In this state, the valve portion 116 closes over the air hole 40. On the other hand, when the inside of the water supply pipe 12 becomes negative pressure, as shown in FIG. 15, the valve part 116 is turned up by the pressure difference or the water pressure of the water flowing back through the water supply pipe 12, and the air hole 40 is opened to prevent siphon. Is done.

  Furthermore, the intake valve 122 shown in FIG. 16 can be used as a siphon prevention means. The intake valve 122 has a valve portion 126 and a hinge 128 attached to a short pipe 124. The short pipe 124 includes a vent hole 130 that communicates with the air hole 40, is inserted into the water supply pipe 12, and is fixed to the water supply pipe 12 with a bolt or the like. The valve portion 126 is formed in a shape obtained by obliquely cutting a prism, and a water stop sheet 132 is attached to the bottom surface of the valve portion 126. A hinge 128 is disposed on the valve portion 126, and the side surface of the valve portion 126 and the short pipe 124 are connected by the hinge 128. Accordingly, when the water flows downward in the water supply pipe 12, the water hits the side surface of the valve portion 126, and the hinge 128 is opened by water pressure. The hole 40 is closed. On the other hand, when water flows backward into the water supply pipe 12 due to the negative pressure in the water supply pipe 12, as shown in FIG. 17, the backflow water hits the slope, and the hinge 128 closes due to the water pressure, so that the valve portion 126 falls and the air hole 40 opens and siphoning is prevented.

  The intake valve shown in the above embodiment can be used not only for a water supply pipe for supplying water to a cultivated land but also for a water supply pipe for supplying water to a green zone such as a park, a sidewalk or a central separation zone.

  A water level management device 36 according to an embodiment of the present invention shown in FIG. 18 is substantially the same as the water level management device 36 shown in FIG. 1, and common portions are denoted by the same reference numerals and description thereof is omitted.

  The water level controller 36 is provided in the branch pipe 22 of the water supply pipe 12 that supplies water, and includes a float 38, a valve body 28, and siphon prevention means. The siphon prevention means is the air hole 40 and the intake valve 42 shown in FIGS. 5 to 8, and is provided at the tip portion 26 above the float 38. However, these positions are not particularly limited as long as they are the branch pipes 22 above the float 38, and the air holes 40 and the intake valves 42 may be provided in the main body 24. Further, the siphon prevention means is not limited to the intake valve 42, and may be the intake valves 92, 112, 122 shown in FIGS. 12 to 17, or other forms.

  For example, when the water level controller 36 is accommodated in a water tank connected to a laying pipe, the water level of the water tank substantially matches the ground water level, and the float 38 floats on the water surface of the water tank, and the water supply pipe 12 serves as a guide for the cultivation area. Interlocks with the groundwater level. Thereby, the valve body 28 connected to the float 38 closes the water supply port of the water supply pipe 12 when the float 38 rises, and conversely opens the water supply port of the water supply pipe 12 when the float 38 descends. The air hole 40 and the intake valve 42 above the float 38 are located in the atmosphere, and when negative pressure is generated in the water supply pipe 12, outside air is sucked into the water supply pipe 12 through the intake valve 42 to prevent siphoning of the water supply pipe 12. To do.

  In all the embodiments described above, “above the float 38” means above the groundwater level when the float 38 is floating, and indicates a position above the groundwater level design height.

  Furthermore, the specific numerical values of the angles and dimensions mentioned above are merely examples, and can be appropriately changed as necessary.

  Further, although the finger pinching prevention cover 80 is used in the embodiment of the water level management device, it may not be used.

  Furthermore, in FIG. 2, FIG. 3, FIG. 9, and FIG. 11, the finger pinching prevention cover 80 is not shown for convenience so that the link mechanism 60 and the like can be easily understood.

It is an illustration figure which shows the underground irrigation system of one Example of this invention. FIG. 2 is a cross-sectional view showing a state where the groundwater level W of the cultivated land is lower than the groundwater level set value S in the underground irrigation system of FIG. 1. FIG. 2 is a cross-sectional view showing a state where the groundwater level W of the cultivated land is higher than the groundwater level set value S in the underground irrigation system of FIG. 1. FIG. 2 is a partial cross-sectional view of a part of the underground irrigation system of FIG. 1, showing a water supply pipe, a water level manager, and a laying pipe. It is a top view which shows the side surface of an intake valve. It is a top view which shows the front of an intake valve. It is a top view which shows the bottom face of an intake valve. It is sectional drawing which shows the state which fitted the protrusion in the receiving hole of the water supply pipe, fixed the intake valve to the water supply pipe, and blocked the air hole by the valve part. It is a top view which shows the front of the water level management device of FIG. It is a top view which shows the side surface of the water level management device of FIG. It is a top view which shows the front of the water level management device of FIG. It is sectional drawing which shows the state which provided the intake pipe in the water supply pipe | tube in the underground irrigation system of another Example of this invention. It is sectional drawing which shows the state which fixed the intake valve to the water supply pipe | tube in the underground irrigation system of another Example of this invention, and opened the air hole. It is sectional drawing which shows the state which fixed the intake valve to the water supply pipe | tube in the underground irrigation system of another Example of this invention, and blocked the air hole by the valve part. FIG. 15 is a cross-sectional view showing a state in which the valve portion is turned up and an air hole is opened in the intake valve of FIG. 14. It is sectional drawing which shows the state which fixed the intake valve to the water supply pipe | tube in the underground irrigation system of another Example of this invention, and blocked the air hole by the valve part. It is sectional drawing which shows the state which the valve part fell in the intake valve of FIG. 16, and the air hole was opened. It is a top view which shows the water level management device of one Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Underground irrigation system 12 ... Water supply pipe 14 ... Laying pipe 18 ... Cultivated land 28 ... Valve body 34 ... Water supply port 36 ... Water level controller 38 ... Float 40 ... Air hole 42, 92, 112, 122 ... Intake valve 88 ... Intake air tube

Claims (5)

A water supply pipe for supplying water,
An underground irrigation system comprising: a laying pipe that is laid on a cultivated land and that supplies water supplied from the water supply pipe to the cultivated land; and a siphon prevention means that sucks outside air into the water supply pipe to prevent siphon.   The said siphon prevention means includes an intake valve that closes an air hole provided in the water supply pipe above the groundwater level of the cultivated land and opens the air hole by a negative pressure in the water supply pipe. Underground irrigation system. A water level manager provided in the water supply pipe;
The water level controller is connected to the float linked to the groundwater level of the cultivated land with the water supply pipe as a guide, and closes the water supply port of the water supply pipe when the float rises, and the float descends A valve body that opens the water supply port of the water supply pipe;
The underground irrigation system according to claim 2, wherein the intake valve is disposed above the float.   The underground irrigation system according to claim 2 or 3, wherein the intake valve is formed of an elastic material, is disposed on an inner surface of the water supply pipe, is fixed above the air hole, and opens the air hole by elastic deformation. A water level controller provided in a water supply pipe for supplying water,
A float linked to the groundwater level of the cultivated land with the water pipe as a guide,
A valve body connected to the float and closing the water supply port of the water supply pipe when the float is raised, and opening the water supply port of the water supply pipe when the float is lowered; and provided above the float and in the water supply pipe A water level controller comprising siphon prevention means for inhaling outside air to prevent siphon.

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