Emitter, and drip irrigation tube

This emitter (120) includes a channel which spans to a recessed section (252), from an intake path (221) for receiving an irrigation liquid inside a tube. The channel includes an aperture (243) which is closed by a lid (244) disposed so as to not be in contact with a film (300). A groove is formed at the periphery of the aperture (243). When the film (300) is pressed as a result of the pressure of the irrigation liquid inside the tube, and the lid (244) closes the aperture (243), the flow rate of the irrigation liquid inside the emitter (120) is controlled so as to be the amount capable of passing through the groove. This flow-rate control continues until the pressure difference in the channel between a side upstream with respect to the lid (244) and a side downstream with respect to the lid (244) has been sufficiently reduced.

TECHNICAL FIELD

The present invention relates to an emitter and a trickle irrigation tube including the emitter.

BACKGROUND ART

A trickle irrigation method is known as a method for culturing plants. In the trickle irrigation method, for example, a trickle irrigation tube is disposed on the soil in which plants are planted, and irrigation liquid such as water and liquid fertilizer is slowly supplied from the trickle irrigation tube to the soil. The trickle irrigation method can minimize the consumption amount of the irrigation liquid, and has been increasingly attracting attention in recent years.

The trickle irrigation tube typically has a tube and an emitter (also called “dripper”). The emitter typically supplies the soil with the irrigation liquid in the tube at a predetermined rate at which the irrigation liquid is dropped to the soil. Emitters which are pierced into the tube from the outside, and emitters joined to the inner wall surface of the tube are known.

For example, the latter emitter has a channel including a pressure reduction channel for allowing the irrigation liquid having entered the emitter from the internal space of the tube toward the through hole of the tube while reducing the pressure of the liquid, and a diaphragm part configured to change the volume of a portion of the channel where the irrigation liquid having reduced pressure flows in accordance with the pressure of the liquid in the tube. The emitter is composed of a member which is joined to the inner wall surface of the tube, a member which is disposed on the member joined to the inner wall surface, and a diaphragm part which is disposed between the two members. The diaphragm part is composed of an elastic film such as a silicone rubber film (see, for example, PTL 1).

The emitter can suppress variation of the discharge rate of the irrigation liquid regardless of change of the pressure of the irrigation liquid in the tube. Therefore, the emitter is advantageous from the viewpoint of uniformly growing multiple plants.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

The emitter is formed by assembling three components. In view of this, the emitter may cause assembling error. In particular, the assembling error of the diaphragm part may cause variation of the operation of the diaphragm part, and variation of the discharge rate of the irrigation liquid.

In addition, the emitter is typically a molded article of an inexpensive resin such as polyethylene and polypropylene, and the diaphragm part is composed of a more expensive elastic material such as a silicone rubber film. The use of components of different materials has a room for improvement in material cost reduction.

Generally, in a trickle irrigation tube, hundreds of emitters are disposed in one tube in some cases. In a long trickle irrigation tube, the supply pressure of irrigation liquid to the tube is required to be increased, and consequently the discharge rate of the irrigation liquid of the emitter may not be stable. In view of this, control of the discharge rate of the irrigation liquid of the emitter in accordance with the pressure of the irrigation liquid in the tube is desired.

Furthermore, from the viewpoint of reducing the material cost and the manufacturing cost of the emitter, an emitter which can be manufactured with a single inexpensive material and fewer number of components is desired.

An object of the present invention is to provide an emitter which can stabilize the discharge rate of the irrigation liquid and can further reduce the manufacturing cost. In addition, another object of the present invention is to provide a trickle irrigation tube having the emitter.

Solution to Problem

The present invention provides an emitter for quantitatively discharging irrigation liquid in a tube to outside of the tube, the tube being configured for allowing the irrigation liquid to flow therethrough, the emitter being configured to be disposed on the tube and including: an intake part for receiving the irrigation liquid in the tube; a pressure reduction channel for allowing the irrigation liquid received from the intake part to flow therethrough while reducing a pressure of the irrigation liquid; a flow rate controlling part for controlling a flow rate of the irrigation liquid supplied from the pressure reduction channel in accordance with a pressure of the irrigation liquid in the tube or in the intake part; and a discharge part which is supplied with the irrigation liquid which has a flow rate controlled by the flow rate controlling part and is to be discharged to the outside of the tube; the flow rate controlling part including: a valve element for opening and closing a channel of the irrigation liquid, a valve seat on which the valve element sits when the valve element closes the channel of the irrigation liquid, a film for pushing the valve element toward the valve seat by being bent under the pressure of the irrigation liquid in the tube or in the intake part such that the valve element sits on the valve seat, and a groove formed on a surface of the valve seat, and configured to communicate between the channel of the irrigation liquid on an upstream side of the valve seat and the channel of the irrigation liquid on a downstream side of the valve seat when the valve element sits on the valve seat. The film pushes the valve element such that the valve element sits on the valve seat when the pressure of the irrigation liquid in the tube is equal to or higher than a predetermined value.

In addition, the present invention provides a trickle irrigation tube includes: a tube; and at least one emitter, the emitter being the above-mentioned emitter.

Advantageous Effects of Invention

The emitter according to the present invention controls the discharge rate of the irrigation liquid in accordance with the pressure of the irrigation liquid in the trickle irrigation tube, and thus can stabilize the discharge rate of the irrigation liquid. In addition, since the emitter according to the present invention can be formed with one or two components by injection molding of a resin material, the manufacturing cost can be further reduced in comparison with conventional emitters composed of three parts.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. It is to be noted that the shapes in plan view, the size, the angle and the pressure in the following embodiments are merely examples, and may be appropriately changed as long as desired functions of the components of the embodiments are achieved.

Configuration

FIG. 1is a schematic sectional view of a trickle irrigation tube according to Embodiment 1 of the present invention. Trickle irrigation tube100is composed of tube110and emitter120. Tube110is made of polyethylene, for example. Emitter120is disposed at a predetermined interval (for example, 200 to 500 mm) in the axial direction of tube110. Each emitter120is joined on the inner wall surface of tube110. Emitter120is disposed at a position where emitter120covers discharge port130of tube110. Discharge port130is a hole which extends through the tube wall of tube110. The hole diameter of discharge port130is, for example, 1.5 mm. It is to be noted that arrow F indicates the direction of flow of the irrigation liquid in tube110.

FIG. 2Aillustrates a top surface, a front surface and a side surface of emitter120, andFIG. 2Billustrates a bottom surface, a front surface and a side surface of emitter120. In addition,FIG. 3Ais a plan view of emitter120,FIG. 3Bis a rear view of emitter120, andFIG. 3Cis a side view of emitter120. In addition,FIG. 4Ais a sectional view of emitter120taken along line A-A ofFIG. 3A, andFIG. 4Bis a sectional view of emitter120taken along line B-B ofFIG. 3A. In addition,FIG. 5Ais a bottom view of emitter120, andFIG. 5Bis a sectional view of emitter120taken along line A-A ofFIG. 5A. It is to be noted that the X direction is the axial direction of tube110or the longitudinal direction of emitter120, the Y direction is the short (width) direction of emitter120, and the Z direction is the height direction of emitter120. In addition, the direction of arrow F is parallel to the X direction.

As illustrated inFIG. 2AandFIG. 2B, emitter120has a cuboid-like external shape. For example, the length of emitter120is 30 mm in the X direction, 10 mm in the Y direction, and 3 mm in the Z direction. Emitter120includes emitter main body200to be joined to the inner wall surface of tube110, and film300which is formed integrally with emitter main body200.

FIG. 6Aillustrates a top surface, a front surface and a side surface of emitter120in the state before film300is joined to emitter main body200, andFIG. 6Billustrates a bottom surface, a front surface and a side surface of emitter120. In addition,FIG. 7Ais a plan view of emitter120in the state before film300is joined to emitter main body200,FIG. 7Bis a rear view of the emitter120, andFIG. 7Cis a side view of the emitter120. Further,FIG. 8Ais a sectional view of emitter120taken along line A-A ofFIG. 7Ain the state before film300is joined to emitter main body200, andFIG. 8Bis a sectional view of the emitter120taken along line B-B ofFIG. 7A. In addition,FIG. 9Ais a bottom view of emitter120in the state before film300is joined to emitter main body200, andFIG. 9Bis a sectional view of the emitter120taken along line A-A ofFIG. 9A.

As illustrated inFIG. 3BandFIG. 3C, emitter main body200includes first surface201and second surface202. First surface201is one surface which is joined to film300in the Z direction of emitter main body200. Second surface202is the other surface which is joined to the inner wall surface of tube110in the Z direction of emitter main body200.

As illustrated inFIG. 6A,FIG. 6B,FIG. 7AandFIG. 8A, emitter main body200includes recesses211and212formed on first surface201, linear protrusions213and214disposed in recesses211and212, intake channel221extending through emitter main body200in the Z direction, and flow rate regulation valve223disposed in intake channel221.

As illustrated inFIG. 6AandFIG. 7A, recess211is a recess located at a center portion of first surface201. The shape (hereinafter also referred to as “shape in plan view”) of recess211as viewed from the Z direction is a rectangular shape.

Recess212is a recess located at first surface201and configured to connect recess211and intake channel221. As illustrated inFIG. 7B, the length of recess212in the Y direction is equal to the diameter of an opening part of intake channel221described later.

As illustrated inFIG. 6AandFIG. 7A, linear protrusions213are a plurality of linear protrusions disposed in recess211side by side in the X direction, and the longitudinal direction of protrusions213is aligned in the Y direction. In plan view, linear protrusion213has a rectangular shape. A gap is provided between linear protrusions213in the X direction, and between linear protrusion213and the wall surface of recess211in the Y direction.

Linear protrusions214are a plurality of linear protrusions disposed side by side in the Y direction in recess212, and the longitudinal direction of linear protrusions214is aligned with the X direction. In plan view, linear protrusion214has a shape which is obtained by cutting out one end of a rectangular in an arc shape. A gap is provided between linear protrusions214in the Y direction, and between an end of linear protrusion214and linear protrusion213adjacent to linear protrusion214in the X direction.

The distance from the bottom surface of recesses211and212to the tip end surface of linear protrusions213and214(the height of linear protrusion213and linear protrusion214) is, for example, 0.5 mm.

The shape of the opening of intake channel221at first surface201is a circular shape as illustrated inFIG. 7A. Intake channel221has an opening diameter of, for example, 5 mm. As illustrated inFIG. 9A, the shape of the opening of intake channel221at second surface202is a shape (bell shape) which is formed with a semicircle of the above-mentioned circle and a rectangular which has a width of the diameter of the opening and extends in the Y direction from the diameter of the semicircle.

As illustrated inFIG. 7AandFIG. 9A, flow rate regulation valve223is composed of four flexible opening-closing parts which closes intake channel221. As illustrated inFIG. 8AandFIG. 9A, the opening-closing parts have a form in which a substantially hemisphere thin dome protruding from first surface201side toward second surface202side is divided with slits in a cross shape. The opening-closing part has a thickness of, for example, 0.5 mm, and, normally, the slit has a width of, for example, 0 mm.

As illustrated inFIG. 5AandFIG. 9A, groove231is connected with intake channel221. Groove231is a linear groove formed on second surface202and extending along the X direction.

As illustrated inFIG. 5AandFIG. 9A, groove232is connected with groove231. Groove232is a groove formed on second surface202and extending along the X direction. In plan view, groove232has a zigzag shape. In the zigzag shape, protrusions having a substantially triangular shape protruding from the side surface of groove232are alternately disposed along the extending direction (the X direction) of groove232. The protrusions are disposed such that the tip of each protrusion does not exceed the central axis line of groove232in plan view. Groove232has a depth of, for example, 0.5 mm, and groove232has a width (W inFIG. 5) of, for example, 0.5 mm.

As illustrated inFIG. 5AandFIG. 9A, groove233is connected with groove232. Groove233is a linear groove formed on second surface202and extending along the X direction.

As illustrated inFIG. 5AandFIG. 9A, hole234opens at an end portion of groove233. The opening shape of hole234is a rectangular shape. As illustrated inFIG. 5BandFIG. 9B, hole234opens at first surface201. Grooves231and233and hole234have a width (the length in the Y direction) of, for example, 1 mm.

As illustrated inFIG. 6A,FIG. 7AandFIG. 8A, emitter main body200further includes groove241formed on first surface201, recess242formed on first surface201, hole243which opens at the bottom of recess242and communicates with second surface202side, flap244which can open and close hole243, and groove245formed at the opening part of hole243.

As illustrated inFIG. 7A, groove241is a linear groove formed on first surface201and extending along the Y direction and in plan view, groove241has a rectangular shape. Hole234opens at one end of groove241and recess242is connected with the other end of groove241.

As illustrated inFIG. 7A, recess242is a bottomed recess formed on first surface201. In plan view, recess242has a circular shape. The opening diameter of recess242is, for example, 6 mm, and the depth of recess242is, for example, 2 mm. As illustrated inFIG. 7AandFIG. 8B, the bottom surface of recess242includes plane part246which has an arch shape in plan view and has a smaller size, and a part (tilted part247) which has an arch shape having a greater size in plan view and is tilted from groove241side toward first surface201. Plane part246is a plane which is parallel to first surface201, and since recess251described later is located on a side opposite to recess242in the Z direction, plane part246is formed in a thin plate shape and has a thickness of, for example, 0.2 mm.

As illustrated inFIG. 8B, hole243opens at tilted part247in such a manner as to make contact with bottom edge of tilted part247. As illustrated inFIG. 9A, hole243has a regular triangular shape in plan view.

As illustrated inFIG. 7A, flap244includes flap plate248and protrusion249protruding from flap plate248. In plan view, flap244has a regular triangular shape as illustrated inFIG. 7A, which is identical to the shape of hole243in plan view. Thus, as viewed along the axis direction of hole243(the Z direction), the shape of flap244is identical to that of hole243. The length of the base end edge of flap plate248(a side of the opening shape of hole243) is, for example, 4 mm. In addition, the length (L inFIG. 8B) of protrusion249in the Y direction is, for example, 2.7 mm.

As illustrated inFIG. 7AandFIG. 8B, flap plate248is composed of a thin plate part which is bent with one side of the opening shape of hole243as a fold line part. Thus, flap244is configured integrally with emitter main body200so as to be turnable about the fold line part. Thus, the opening shape of hole243includes a linear part, and flap244has a linear fixed end at the linear part and is configured to be turnable about the fixed end. It is to be noted that flap plate248has a thickness of, for example, 0.2 mm.

In addition, as illustrated inFIG. 8B, flap plate248is tilted with respect to plane part246more than tilted part247. For example, the inclination angle θ1of tilted part247to the surface of plane part246is 19°, and inclination angle θ2of flap plate248to the bottom surface and the surface of plane part246is 26.6°. In plan view, the size of the gap between hole243and flap244is largest at a position between the apex of hole243and a tip end (apex) of flap244, and the size of the gap at that position is, for example, 0.5 mm. Thus, as viewed along an axis for the turning (in the Y direction), flap plate248where flap244makes close contact with the opening edge of hole243is disposed obliquely to tilted part247which includes other portions than the linear part the opening edge of hole243in a non-contact manner.

In plan view, protrusion249has a triangular shape and is included in the shape of flap244as illustrated inFIG. 7A. To be more specific, protrusion249has a triangular shape in plan view, and each side surface of protrusion249is composed of a tapered surface which is tilted from hole243side toward the opening part of recess242at each side of the triangular shape as illustrated inFIG. 7AandFIG. 8A. With this configuration, protrusion249has an isosceles triangular shape in plan view, and the length of the base is, for example, 2.1 mm. As illustrated inFIG. 8B, the top surface of protrusion249is parallel to the opening edge of recess242. In the Z direction, the distance between the opening edge and the top surface is, for example, 0.2 mm.

As illustrated inFIG. 7A, groove245is a groove which is formed on the surface of tilted part247and is connected with the apex of the opening shape of hole243. Groove245has a width of, for example, 0.25 mm, and groove245has a depth from tilted part247of, for example, 0.1 mm.

As illustrated inFIG. 9A, each of recesses251,252and253is a recess formed on second surface202. In plan view, recess251has a circular shape, and hole243opens at the bottom of recess251. In plan view, recess252has a rectangular shape, and linear protrusion254is disposed on the bottom of recess252. Recess253is a recess which connects recess251and recess252, and is shallower than the recesses. In the Y direction, recess253has a length smaller than the length of recess252.

As illustrated inFIG. 9A, linear protrusion254is a slender linear protrusion extending along the Y direction. In plan view, linear protrusion254has a rectangular shape, and the length of linear protrusion254in the Y direction is smaller than the length of recess252in the Y direction and is substantially equal to the length of recess253in the Y direction. In the X direction, linear protrusion254is disposed at a position near recess253but is separated from recess253. Thus, as viewed from recess252side along the X direction, linear protrusion254is disposed at a position where linear protrusion254overlaps recess253.

As illustrated inFIG. 7AandFIG. 9A, film300is disposed integrally with emitter main body200through hinge part301. Hinge part301is disposed at an edge of first surface201of emitter main body200in the Y direction. For example, hinge part301is a portion having a thickness equal to that of film300and a width of 0.5 mm, and is formed integrally with emitter main body200and film300.

As illustrated inFIG. 7AandFIG. 9A, film300further includes rectangular opening part302at a position corresponding to first recess211in the state where film300covers first surface201. For example, the thickness of film300may be determined by a computer simulation or an experiment using a trial product or the like on the basis of the deformation amount under a pressure described later, and may be, for example, 0.15 mm.

Each of emitter main body200and film300is molded with one material having flexibility such as polypropylene, for example. Examples of the material include resin and rubber, and examples of the resin include polyethylene and silicone. The flexibility of emitter120and film300can be adjusted with use of elastic resin materials, and for example, can be adjusted by the type of an elastic resin, the mixing ratio of an elastic resin material to a hard resin material, and the like. Emitter120can be manufactured as an integrally molded member by injection molding, for example.

Film300turns about hinge part301, and is closely joined on first surface201of emitter main body200. For example, the joining is performed by welding of a resin material of emitter main body200or film300, by bonding using an adhesive agent, by pressure bonding of film300to emitter main body200or the like.

As illustrated inFIG. 2AandFIG. 4A, when film300is joined to first surface201, intake channel221and recess212are covered with film300, and the gap between linear protrusions214opens at recess211and forms a plurality of channels connected with intake channel221. Thus, when film300is joined to first surface201, intake channel221and the gap constitute an intake part for receiving the irrigation liquid in tube110.

In addition, when film300is joined to first surface201, groove241and recess242are covered with film300as illustrated inFIG. 4AandFIG. 4B. The gap between recess242and film300constitute a channel for irrigation liquid. When film300is joined to first surface201, recess242, hole243and flap244constitute a flow rate controlling part for controlling the flow rate of the irrigation liquid supplied from a pressure reduction channel described later in accordance with the pressure of the irrigation liquid in tube110.

Flap244is disposed at a position separated from film300such that flap244can open and close hole243. Flap244serves as a valve element for opening and closing hole243which forms a channel for irrigation liquid. In addition, as described later in detail, flap plate248makes close contact with the opening edge of hole243when flap244is closed. Thus, the opening edge of hole243serves as a valve seat on which flap244sits when flap244closes hole243.

Second surface202is joined to the inner wall surface of tube110. This joining is also performed by welding of the resin material of emitter main body200or tube110, by bonding using adhesive agent, by pressure bonding of emitter main body200to tube110, or the like.

When second surface202is joined to the inner wall surface of tube110, second surface202makes close contact with tube110, and intake channel221and grooves231to233are covered with tube110. When grooves231to233is covered with tube110, grooves231to233and hole234constitute a channel through which the irrigation liquid received from the intake part flows. Among them, groove232serves as a pressure reduction channel for allowing the irrigation liquid to flow therethrough while reducing the pressure of the irrigation liquid.

In addition, when second surface202is joined to the inner wall surface of tube110, recesses251,252and253are covered with tube110. Discharge port130is disposed at a position where tube110covers recess252. In this manner, when second surface202is joined to tube110, recess252constitutes a discharge part to which the irrigation liquid having a flow rate controlled by the flow rate controlling part is supplied and which is configured to face discharge port130.

Normally, emitter120is joined to the inner periphery wall of tube110before discharge port130is formed, and thereafter, discharge port130is formed at a position corresponding to discharge part (recess252) of tube110. Alternatively, emitter120may be joined to the inner wall surface of tube110such that emitter120is located at the position of preliminarily provided discharge port130.

Next, discharge of irrigation liquid by emitter120is described.FIG. 10Aillustrates part A ofFIG. 4Bin an enlarged manner in the case where the pressure of the irrigation liquid in tube110is equal to or higher than the first pressure value and lower than the second pressure value,FIG. 10Billustrates part A ofFIG. 4Bin an enlarged manner in the case where the pressure of the irrigation liquid in tube110is equal to or higher than the second pressure value, andFIG. 10Cillustrates part A ofFIG. 4Bin an enlarged manner in the case where the pressure of the irrigation liquid in tube110is reset to a pressure equal to or higher than the first pressure value and lower than the second pressure value.

Supply of the irrigation liquid to trickle irrigation tube100is performed in a range where the pressure of the irrigation liquid does not exceed 0.1 MPa for example in view of preventing the damaging of tube110and emitter120. When the irrigation liquid is supplied into tube110, the irrigation liquid reaches recess212covered with film300in the Z direction through the gap between recess211and linear protrusion213, and reaches intake channel221through the gap between recess212and linear protrusion214. Recess211and linear protrusion213, and recess212and linear protrusion214constitute a channel for the irrigation liquid and prevent intrusion of floating materials in the irrigation liquid larger than the gap between the linear protrusions. In this manner, recesses211and212and linear protrusions213and214function as a filter.

When the pressure of the irrigation liquid in tube110is equal to or higher than the first pressure value (for example, 0.005 MPa), flow rate regulation valve223is pushed to second surface202side, and the slit of flow rate regulation valve223is expanded. In this manner, the irrigation liquid reaching intake channel221is received into emitter main body200from intake channel221. Flow rate regulation valve223suppresses inflow of the irrigation liquid to emitter main body200when the pressure of the irrigation liquid is lower than the first pressure. Thus, high-pressure supply of the irrigation liquid to tube110can be achieved, and therefore the configuration in which emitter120has flow rate regulation valve223is favorable for forming trickle irrigation tube100having a greater length, for example.

The irrigation liquid received from intake channel221is supplied to groove232(pressure reduction channel) through groove231. The pressure of the irrigation liquid flowing through groove232is reduced as a result of pressure loss caused by the shape (zigzag shape) in plan view of groove232. In addition, floating materials in the irrigation liquid are entangled in the turbulent flow generated between the protrusions of groove232and are retained in groove232. In this manner, the floating materials are further removed from the irrigation liquid by pressure reduction channel230.

In addition, since the tip of the protrusion is disposed in such a manner that the tip does not exceed the center line of groove232in plan view, a space which is not blocked by the protrusion is formed at the center of groove232while the width of the space is small, and thus the irrigation liquid easily flow through groove232. Accordingly, in addition to the effect of reducing pressure and the effect of removing the floating material, groove232is favorable for allowing irrigation liquid to flow with a greater flow rate.

The irrigation liquid having passed through groove232in which the pressure is reduced and the floating material is removed is supplied to recess242through groove233, hole234, and groove241. The gap between film300and recess242is filled with the irrigation liquid, and the irrigation liquid is supplied to hole243(FIG. 10A).

The irrigation liquid having passed through hole243reaches recess252through recessed251and253and is then discharged out of tube110through discharge port130which faces recess252and opens at recess252.

It is to be noted that foreign matters such as soil may intrude into recess252from discharge port130, intrusion of such foreign matters into hole243is blocked by linear protrusion254disposed in recess252.

As the pressure of the irrigation liquid in tube110increases, the flow rate of the irrigation liquid to be received into emitter main body200from intake channel221increases, and the discharge rate of the irrigation liquid from discharge port130increases.

When the pressure of the irrigation liquid in tube110is equal to or higher than a second pressure value (for example 0.02 MPa), film300bends under the pressure of the irrigation liquid in tube110, and pushes flap244toward hole243as illustrated inFIG. 10B. Flap244and hole243have the same shape in plan view, and the bottom surface of flap plate248is tilted with respect to tilted part247where hole243opens by a slight angle (by angle obtained by subtracting θ1from θ2). Accordingly, since one side of the triangular shape is the fixed end, the distance from the fixed end to two sides of flap plate248along the bottom surface of flap plate248is greater than the distance from the fixed end to the two sides of hole243along the opening edge of hole243. Thus, flap plate248covers the opening part of hole243, and the peripheral portion of flap plate248of flap244serving as a valve element makes close contact with (sits on) the opening edge of hole243serving as a valve seat. Thus, flap244functions as a valve element which seals hole243serving as a channel for irrigation liquid, and the opening edge of hole243functions as a valve seat on which the valve element sits.

However, since groove245is formed on the surface of the opening edge of hole243serving as a valve seat, groove245communicates between the inside of recess242which is a channel on the upstream side relative to the valve seat of irrigation liquid and hole243which is a channel on the downstream side of the valve seat when flap244serving as the valve element sits on the valve seat. In this manner, the irrigation liquid supplied to recess242is supplied to hole243through groove245.

Consequently, the amount of the irrigation liquid which passes through the flow rate controlling part is restricted to a flow rate which can pass through groove245, and the discharge rate of the irrigation liquid from discharge port130becomes substantially constant. In this manner, emitter120quantitatively discharges the irrigation liquid from tube110supplied with the irrigation liquid.

When hole243is closed by flap244, the pressure in recess242is normally high relative to the pressure in hole243. Accordingly, as illustrated inFIG. 10C, even when the pressure of the irrigation liquid in tube110is reduced to a pressure lower than the second pressure value, a pressure difference obtained by subtracting the inner pressure of hole243from the inner pressure of recess242is a positive pressure, and in addition, in the case where the inner pressure of recess242is greater than the elastic force of returning to the initial position of flap244, flap244keeps closing hole243even when the pressure of the irrigation liquid in tube110is once increased to the second pressure value and thereafter reduced to a value lower than the second pressure value. Thus, the amount of the irrigation liquid passing through the flow rate controlling part is continuously restricted to the flow rates which can pass through groove245.

When the irrigation liquid in recess242sufficiently flows through groove245, the inner pressure of recess242is sufficiently reduced. Then, when the pressure difference is reduced to a value smaller than the elastic force, flap244returns to the initial position with the elastic force, and hole243is opened as illustrated inFIG. 10A. Then, the irrigation liquid in recess242again flows to hole243through the gap between flap244and the opening part of hole243.

As described, emitter120is an emitter for quantitatively discharging irrigation liquid in tube110to outside of tube110, tube110being configured for allowing the irrigation liquid to flow therethrough, emitter120being configured to be disposed on tube110and including: the intake part for receiving the irrigation liquid in tube110; the pressure reduction channel for allowing the irrigation liquid received from the intake part to flow therethrough while reducing a pressure of the irrigation liquid; the flow rate controlling part for controlling a flow rate of the irrigation liquid supplied from the pressure reduction channel in accordance with a pressure of the irrigation liquid in tube110or in the intake part; and the discharge part which is supplied with the irrigation liquid which has a flow rate controlled by the flow rate controlling part and is to be discharged to the outside of tube110; the flow rate controlling part including: the valve element for opening and closing a channel of the irrigation liquid, the valve seat on which the valve element sits when the valve element closes the channel of the irrigation liquid, film300for pushing the valve element toward the valve seat by being bent under the pressure of the irrigation liquid in tube110or in the intake part such that the valve element sits on the valve seat, and groove233formed on a surface of the valve seat, and configured to communicate between the channel of the irrigation liquid on an upstream side of the valve seat and the channel of the irrigation liquid on a downstream side of the valve seat when the valve element sits on the valve seat. Then, when the pressure of the irrigation liquid in tube110is equal to or higher than a predetermined value, film300pushes the valve element to sit the valve element on the valve seat. Thus, emitter120can stabilize the discharge rate of the irrigation liquid. Further, emitter120may be composed of two injection-molded articles at most. Therefore, emitter120can further reduce manufacturing cost in comparison with conventional emitters composed of three parts.

In addition, emitter120has the configuration in which emitter120is an emitter for quantitatively discharging the irrigation liquid in tube110from the discharge port, emitter120being configured to be joined to an inner wall surface of tube110at a position corresponding to a discharge port configured to communicate between inside and outside of tube110; the flow rate controlling part includes: an opening part (recess242) for forming a part of a channel of the irrigation liquid on a downstream side of the pressure reduction channel in emitter120, the opening part opening at a surface of emitter120at a position (first surface201) where the surface of emitter120is not joined to the inner wall surface, film300configured to seal the opening part and block communication between the channel on the downstream side of the pressure reduction channel and the inside of tube110, hole243opening at the channel on the downstream side of the pressure reduction channel to face film300, hole243243being communicated with the discharge part, and the valve element (flap244) disposed such that the valve element forms a gap between flap244at least a part of an opening edge of the hole and is allowed to make contact with the opening edge and allowed to be separated from the opening edge; and at least a part of the opening edge of hole243243constitutes the valve seat. This configuration is further effective from the viewpoint of forming the emitter which can achieve the above-mentioned effect and which is to be disposed inside tube110.

In addition, an opening shape of hole243includes a linear part; the valve element includes a linear fixed end at the linear part, and is turnable about the fixed end as a turning axis; the valve element has a shape identical to a shape of hole243as viewed along an axis direction of hole243; and a portion where the valve element makes close contact with the valve seat is disposed obliquely to other portion of the opening edge of hole243other than the linear part without making contact with the other portion as viewed along the turning axis. This configuration makes it possible to form the flow rate controlling part by injection molding with one component, and therefore is further effective from the standpoint of reducing of manufacturing cost.

In addition, with the configuration in which the intake part further includes flow rate regulation valve223for expanding the channel for the irrigation liquid when the pressure of the irrigation liquid in tube110is equal to or higher than a predetermined value, the irrigation liquid can be supplied to tube110with a higher pressure, and therefore the configuration is favorable from the standpoint of forming trickle irrigation tube100having a greater length.

In addition, with the configuration in which emitter120is molded with one material having flexibility and film300is integrally molded as a part of emitter120, emitter120can be produced as one component by injection molding, and therefore the configuration is further effective from the standpoint of reducing manufacturing cost.

In addition, the configuration in which hole243is opened and closed with flap244which opens and closes about the fixed end is favorable for increasing the maximum size of the gap between flap244(valve element) and hole243. This configuration is further effective from the view point of suppressing the clogging of the above-mentioned gap. In addition, a channel having a greater size of irrigation liquid and extending to hole243is formed with opened flap244, and thus the irrigation liquid in recess242easily flows to hole243. Therefore, the configuration is further effective from the view point of increasing the discharge rate of the irrigation liquid, and from the view point of increasing the variation of the flow rate of the irrigation liquid with the opening and closing of flap244.

In addition, once flap244is closed, flap244is kept closed until the pressure difference obtained by subtracting the inner pressure of hole243from the inner pressure of recess242is sufficiently reduced (to a value smaller than the above-described elastic force). Accordingly, when the flow rate of the irrigation liquid in the case where the irrigation liquid flows only through groove245is set to a predetermined discharge rate of emitter120, the flow rate of the irrigation liquid significantly varies depending on the opening and closing of flap244as described above, and thus the discharge rate of emitter120quickly returns to the above-mentioned predetermined discharge rate, which is further effective from the viewpoint of quickly achieving the predetermined discharge rate, and from the viewpoint of maintaining the rate for a long period of time.

In addition, since the configuration in which the turning axis of flap244has a linear shape is favorable for performing the opening and closing of flap244(turning) with a smaller force, the configuration is further effective from the viewpoint of precisely setting the predetermined discharge rate of the irrigation liquid in emitter120.

In addition, since the configuration in which each of hole243and flap244has a triangular shape in plan view is favorable for reducing the contact length of the valve element and the valve seat, the configuration is further effective from the viewpoint of preventing displacement of flap244when flap244seals hole243.

When emitter120is joined to the inner wall surface of tube110, trickle irrigation tube100including tube110and emitter120disposed to tube110is provided. Since trickle irrigation tube100can quickly achieve a predetermined discharge rate and maintain the rate for a long period of time, irrigation liquid can be discharged substantially at the predetermined discharge rate at all times. Accordingly, trickle irrigation tube100is favorably used for growing of plants which requires further precise discharge of irrigation liquid, for example.

In trickle irrigation tube100, the above-described configurations may be partially changed, or other configurations may be additionally provided as long as the above-described effect is achieved.

For example, tube110may be a seamless tube, or a tube composed of slender sheet(s) joined together along the longitudinal direction.

In addition, discharge port130may be a gap formed at the above-mentioned joining part of the sheets so as to communicate between the inside and the outside of tube110, or a pipe sandwiched by the sheets at the joining part. Further, the shape of the discharge port in an axial direction thereof may not be a straight line shape. Examples of the tube having the discharge port include a tube in which a depression having a desired shape and serving as a channel is formed on the surface of the above-mentioned sheet(s), and a discharge port composed of the channel is formed at the joining part when the sheets are joined together.

While intake channel221is located at a position on the upstream side in the flow direction of the irrigation liquid in tube110, intake channel221may be located at a position on the downstream side. In addition, the orientations of a plurality of emitters120in one tube110may be identical to each other or different from each other.

In addition, the resin material of emitter main body200and the resin material of film300may be identical to each other or different from each other.

While emitter main body200is integrally molded by injection molding of resin, emitter main body200may be composed of two components of a first surface201side component and a second surface202side component. In this case, the components on the first surface201side are molded integrally with film300. With the configuration in which emitter main body200is composed of the two components, the above-mentioned pressure reduction channel can be disposed inside emitter main body200, for example. Further, the two components may be integrally molded through a hinge part.

In addition, the channel connecting intake channel221and recess242which include the pressure reduction channel may be composed of a groove on first surface201covered with film300in emitter main body200.

In addition, second surface202may be a curved surface along the inner wall of tube110(for example, a surface defined by the arc whose arc radius is the internal diameter of tube110in the YZ plane).

Further, since it suffices to appropriately dispose flow rate regulation valve223in accordance with the pressure of the irrigation liquid supplied to tube110, emitter120may not be provided with flow rate regulation valve223.

While emitter120preferably include a pressure reduction channel having the above-mentioned shape from the viewpoint of ensuring a predetermined discharge rate, emitter120may not be provided with the pressure reduction channel. For example, while film300bends toward recess242and pushes flap244in accordance with the pressure difference between the pressure of the irrigation liquid in tube110and the pressure of the irrigation liquid in recess242, channels other than the pressure reduction channel having the above-described shape (for example, a simple linear channel) may be adopted as long as the channel from the intake part to the flow rate regulating part sufficiently provides the pressure difference.

While flap244includes protrusion249having a substantially triangular pyramidal trapezoidal shape with a regular triangular bottom surface and an isosceles triangular top surface, flap244may not be provided with protrusion249as long as bending of film300in accordance with a predetermined value of the pressure of the irrigation liquid in tube110is transmitted. For example, flap244may include a rod-shaped protrusion protruding from an end portion of flap244toward film300in place of the above-mentioned shape protrusion249. Alternatively, flap244may be provided with the above-mentioned rod-shaped protrusion for film300to push flap244without being provided with protrusion249.

Now Embodiment 2 of the present invention is described.

FIG. 11is a schematic sectional view of trickle irrigation tube400according to Embodiment 2 of the present invention. Trickle irrigation tube400is composed of tube110and emitter320. The configuration of tube110is identical to that of the above-described Embodiment 1.

FIG. 12Ais a perspective view of emitter320inFIG. 11as viewed from tube110side, andFIG. 12Bis a perspective view of emitter320inFIG. 11as viewed from a side opposite to tube110. In addition,FIG. 13Ais a plan view of emitter320,FIG. 13Bis a front view of emitter320,FIG. 13Cis a bottom view of emitter320,FIG. 13Dis a left side view of emitter320, andFIG. 13Eis a right side view of emitter320. Furthermore, FIG.14A is a sectional view of emitter320taken along line A-A ofFIG. 13A, andFIG. 14Bis a sectional view of emitter320taken along line B-B ofFIG. 13A.

Emitter320includes first cylindrical part410, flange part420connected with first cylindrical part410, second cylindrical part430connected with flange part420on a side opposite to first cylindrical part410, and third cylindrical part440connected with flange part420on first cylindrical part410side. Flange part420is composed of a combination of first plate part450and second plate part460. It is to be noted that the Z direction is a direction along the axis of first cylindrical part410, and includes the direction along which emitter320is inserted to tube110. The X direction is one direction orthogonal to the Z direction, and the Y direction is a direction orthogonal to both of the Z direction and the X direction.

As illustrated inFIG. 12A, first cylindrical part410is a cylindrical member uprightly provided on the surface of first plate part450. As illustrated inFIG. 13AandFIG. 13B, first cylindrical part410is disposed at a center portion of flange part420in plan view.

As illustrated inFIG. 14A, barb411is formed at a tip end portion of first cylindrical part410. Barb411is composed of large diameter part412which expands from the outer peripheral surface of first cylindrical part410along XY plane, and tapered surface413whose outer diameter gradually decreases from large diameter part412toward the tip end of first cylindrical part410. For example, first cylindrical part410has an internal diameter of 2 mm, large diameter part412has an outer diameter of 3.2 mm, the tip end of tapered surface413has an outer diameter of 2.6 mm, and first cylindrical part410has a height from the surface of flange part420of 5 mm.

As with first cylindrical part410, third cylindrical part440is a cylindrical member uprightly provided on the surface of first plate part450as illustrated inFIG. 12A. As illustrated inFIG. 13AandFIG. 13B, third cylindrical part440is disposed at a position shifted from the center of flange part420in the X direction.

As illustrated inFIG. 14A, barb441is formed at a tip end portion of third cylindrical part440. Barb441is composed of large diameter part442which expands from the outer peripheral surface of third cylindrical part440along XY plane, and tapered surface443whose outer diameter gradually decreases from large diameter part442toward the tip end of third cylindrical part440. For example, third cylindrical part440has an internal diameter of 3 mm, large diameter part442has an outer diameter of 4 mm, the tip end of tapered surface443has an outer diameter of 3.3 mm, and third cylindrical part440has a height from the surface of flange part420of 5 mm.

As viewed along the Z direction (as the shape in plan view), flange part420has a circular shape. For example, flange part420has a thickness of 3 mm, and flange part420has an outer diameter of 16 mm.

FIG. 15Ais a plan view of an integrally formed member (hereinafter also referred to as “first member”) of first cylindrical part410, third cylindrical part440and first plate part450,FIG. 15Bis a front view of the first member,FIG. 15Cis a bottom view of the first member,FIG. 15Dis a left side view of the first member, andFIG. 15Eis a left side view of the first member. In addition,FIG. 16is a sectional view of the first member taken along line A-A ofFIG. 15A.

As illustrated inFIG. 14B,FIG. 15CandFIG. 16, first plate part450includes hole451and recess452opening at the surface, and recesses453and454, grooves455and456and linear protrusion457formed on the bottom surface. First plate part450further includes flow rate regulation valve458which covers hole451at the boundary part between hole451and recess453.

As illustrated inFIG. 15AandFIG. 16, hole451opens at a center portion of the surface of first plate part450, and opens at recess453described later. In addition, the opening of hole451on the surface of first plate part450is included in first cylindrical part410. That is, hole451communicates between first cylindrical part410and recess453. In plan view, hole451has a circular shape as illustrated inFIG. 13A. The diameter of hole451is equal to the internal diameter of first cylindrical part410.

As illustrated inFIG. 16, recess452is a recess formed on the surface of first plate part450. In addition, the opening of recess452on the surface of first plate part450is included in third cylindrical part440. That is, recess452is communicated with third cylindrical part440. In plan view, recess452has a circular shape as illustrated inFIG. 13A. The bottom of recess452constitutes film459described later. The diameter of recess452is equal to the internal diameter of third cylindrical part440. In addition, recess452has a depth from the surface of first plate part450of, for example, 0.65 mm.

As illustrated inFIG. 16, recess453is a recess formed at a center portion of the bottom surface of first plate part450. In plan view, recess453has a circular shape as illustrated inFIG. 15C. The diameter of recess453is slightly greater than the internal diameter of first cylindrical part410. Recess453has a depth from the bottom surface of first plate part450of, for example, 0.5 mm.

As illustrated inFIG. 15C, groove455is a groove formed on the bottom surface of first plate part450and connected with recess453. As illustrated inFIG. 15C, groove455extends along the radial direction on the bottom surface of first plate part450from recess453to a peripheral portion of the bottom surface of first plate part450. In plan view, groove455has a zigzag shape similar to that of the groove232, and groove455has a width (inFIG. 15CW) of, for example, 0.45 mm.

As illustrated inFIG. 15C, recess454is a recess formed independently from recess453on the bottom surface of first plate part450at a position adjacent to recess453in the X direction. In plan view, recess454has a rectangular shape. In the Z direction, recess454overlaps recess452on the surface side of first plate part450, and this overlapping part constitutes thin film459. Accordingly, film459has a circular shape in plan view. In this manner, film459is disposed to face recess454. Recess454has a depth from the bottom surface of first plate part450of, for example, 0.2 mm, and film459has a thickness of, for example, 0.15 mm. The thickness of film459is determined by a computer simulation or an experiment using a trial product or the like on the basis of the deformation amount under the pressure described later.

As illustrated inFIG. 15C, groove456is a groove formed on the bottom surface of first plate part450, and connects groove455and recess454. In plan view, groove456has an L shape, and groove456is connected with groove455at an end of the short side of the L-shape and with recess454at an end portion of the long side of the L-shape.

As illustrated inFIG. 15C, linear protrusion457is disposed at a peripheral portion of the bottom surface of first plate part450, and as illustrated inFIG. 16, linear protrusion457protrudes from the bottom surface of first plate part450. In plan view, linear protrusion457has a ring shape as illustrated inFIG. 15C. Linear protrusion457has a height from the bottom surface of first plate part450of, for example, 1 mm.

As with the above-described flow rate regulation valve223, flow rate regulation valve458is composed of four opening-closing parts. As illustrated inFIG. 15CandFIG. 16, the opening-closing part has a form similar to the form in which a substantially hemisphere thin dome covering the opening of recess452side of hole451and protruding toward recess453is divided with slits in a cross shape. The slit has a width of, for example, 0 mm, and the opening-closing part has a thickness of, for example, 0.2 mm.

FIG. 17Ais a plan view of an integrally formed member (hereinafter also referred to as “second member”) of second cylindrical part430and second plate part460,FIG. 17Bis a front view of the second member,FIG. 17Cis a bottom view of the second member,FIG. 17Dis a side view of the second member, andFIG. 17Eis part E of the second member inFIG. 17Ain an enlarged manner. In addition,FIG. 18is a sectional view of the second member taken along line A-A ofFIG. 17A.

As illustrated inFIG. 18, second plate part460includes recess461and linear recess462formed on one surface of (first surface) and recess463formed on the other surface (second surface).

As illustrated inFIG. 18, recess461is a bottomed recess which opens at the first surface of the second plate part. In plan view, recess461has a circular shape. As illustrated inFIG. 18andFIG. 17A, the bottom surface of recess461includes arch-shaped plane part464having a smaller size in plan view, and arch-shaped tilted part465having a greater size in plan view. Plane part464is a planar portion which is parallel to the first surface, and tilted part465is tilted from plane part464toward the first surface. Plane part464has a thickness of, for example, 0.2 mm.

As illustrated inFIG. 18, hole466opens at tilted part465. As illustrated inFIG. 17C, hole466has a triangular shape in plan view.

As illustrated inFIG. 17EandFIG. 18, flap plate468is composed of a thin plate part which is bent from plane part464with one side of the opening shape of hole466as a fold line part. Thus, flap467is formed integrally with second plate part460such that flap467is turnable about the fold line part. In this manner, the opening shape of hole466includes a linear part, and flap467includes a linear fixed end at the linear part such that flap467is turnable about the fixed end. It is to be noted that the fixed end in the Y direction length for example 2.5 to 3 mm. In addition, flap plate468has a thickness of, for example, 0.2 mm.

As illustrated inFIG. 18, flap plate468is further tilted than tilted part465. For example, inclination angle θ1between tilted part465and the surface of plane part464is 19°, inclination angle θ2between the bottom surface of flap plate468and the surface of plane part464is 26.6°. The size of the gap between hole466and flap467is largest at a position between the apex of hole466and a tip end (apex) of flap467. Thus, as viewed along an axis for the turning (in the Y direction), flap plate468where flap467makes close contact with the opening edge of hole466is disposed obliquely to tilted part465including the portions other than the linear part of the opening edge of hole466in a non-contact manner.

In plan view, protrusion469has a triangular shape and is included in the shape of flap467as illustrated inFIG. 17E. To be more specific, while protrusion469has a triangular shape in plan view, each side of protrusion469is composed of a tapered surface tilted from hole466side toward the opening part of recess461at each side of the triangular shape, as with Embodiment 1. Thus, the top surface of protrusion469has an isosceles triangular shape in plan view. As illustrated inFIG. 18, the top surface of protrusion469is parallel to the opening edge of recess461. In the Z direction, the distance between the opening edge and the top surface is, for example, 0.2 mm.

As illustrated inFIG. 17AandFIG. 17E, groove470is a groove which is formed on the surface of tilted part465and is connected with hole466at the apex of the opening shape of hole466. Groove470has a width of, for example, 0.25 mm, and groove470has a depth from tilted part465of, for example, 0.1 mm.

As illustrated inFIG. 17A, linear recess462is disposed at the peripheral portion of the first surface, and is depressed from the second surface as illustrated inFIG. 17BandFIG. 17D. In plan view, linear recess462has a ring shape as illustrated inFIG. 17A. Linear recess462has a depth from the second surface of, for example, 1 mm.

As illustrated inFIG. 18, recess463is disposed at a position where recess463overlaps recess461in the Z direction in the second surface. As is obvious fromFIG. 17CandFIG. 18, recess463has a circular shape in plan view. Hole466opens at the bottom surface of recess463. That is, recess463is communicated with recess461through hole466.

As illustrated inFIG. 12B, second cylindrical part430is a cylindrical member uprightly provided on the second surface of second plate part460. As illustrated inFIG. 13BandFIG. 13C, second cylindrical part430is disposed at a position shifted from the center of the planar shape of flange part420in the X direction on the side opposite to with respect to third cylindrical part440with flange part420therebetween. Second cylindrical part430includes the opening of recess463of the second surface. That is, second cylindrical part430is communicated with recess463. The internal diameter of second cylindrical part430is equal to the diameter of recess463.

As illustrated inFIG. 17BandFIG. 18, barb431is formed at a tip end portion of second cylindrical part430as with first cylindrical part410. Barb431is composed of large diameter part432which expands from the outer peripheral surface of second cylindrical part430along the XY plane, and tapered surface433whose outer diameter gradually decreases from large diameter part432toward the tip end of second cylindrical part430. For example, second cylindrical part430has an internal diameter of 3 mm, large diameter part432has an outer diameter of 5 mm, the tip end of tapered surface433has an outer diameter of 4 mm, and second cylindrical part430has a height from the second surface of second plate part460of 12 mm.

As with emitter main body200of Embodiment 1, each of the first component and the second component is integrally molded by injection molding using one resin material having flexibility (for example, polypropylene). Examples of the material of the first component and the second component include resin and rubber, and examples of the resin include polyethylene and silicone. The flexibility of the material is properly adjusted by the type of the resin material, mixture of two or more resin materials or the like in accordance with the flexibility required for film459.

The first member and the second member are combined with each other by fitting linear protrusion457of first plate part450with linear recess462of second plate part460, and thus emitter320is formed as illustrated inFIG. 12AandFIG. 12B. The bottom surface of first plate part450and the first surface of the second plate part may be joined by welding of a resin material, by bonding using an adhesive agent, by pressure bonding of one of them to the other or the like.

As illustrated inFIG. 14AandFIG. 14B, when the first member and the second member are combined with each other, recess453and grooves455and456illustrated inFIG. 15Care covered with the surface of second plate part460, and thus the channel for irrigation liquid is formed. In addition, the intake part for receiving the irrigation liquid in tube110is composed with first cylindrical part410, hole451and recess453. Groove455constitutes the pressure reduction channel for allowing the irrigation liquid received from the intake part to flow therethrough while reducing the pressure of the irrigation liquid.

In addition, recess454illustrated inFIG. 15Cand recess461illustrated inFIG. 17Aare combined with each other to form a channel on the downstream side relative to the pressure reduction channel of the irrigation liquid. In addition, hole466faces film459and opens at the channel. As illustrated inFIG. 14A, film459is disposed at a position separated from flap467. Flap467is disposed so as to form a gap between the flap467and at least a part of the opening edge of hole466, and constitutes a valve element which is disposed such that it can be brought into contact with the opening edge and can be separated from the opening edge. In this manner, with the combination of recess454and recess461, the flow rate controlling part for controlling the flow rate of the irrigation liquid supplied from the pressure reduction channel in accordance with the pressure of the irrigation liquid in tube110is formed. It is to be noted that second cylindrical part430is communicated with recess461and constitutes the discharge the discharge part which is supplied with irrigation liquid which is to be discharged out of tube110and has a flow rate controlled by the flow rate controlling part.

Flap467is disposed at a position separated from film459such that flap467can open and close hole466. Flap467constitutes a valve element for opening and closing hole466which constitutes a channel for irrigation liquid. In addition, as described later in detail, flap plate468makes close contact with the opening edge of hole466when flap467is closed. In this manner, the opening edge of hole466constitutes a valve seat on which flap467sits when flap467closes hole466.

As illustrated inFIG. 11, emitter320is attached to tube110by inserting first cylindrical part410and third cylindrical part440to the pipe wall of tube110. Attaching of emitter320may be performed by penetrating the pipe wall of tube110with first cylindrical part410and third cylindrical part440, or by inserting first cylindrical part410and third cylindrical part440to an opening part for insertion which is preliminarily formed on the pipe wall of tube110. The former is favorable for arbitrarily disposing emitter320on tube110, and the latter is favorable for preventing leakage of irrigation liquid from tube110. Since each of first cylindrical part410and third cylindrical part440includes a barb at the tip end portion thereof, dropping of emitter320from tube110is prevented.

It is to be noted that second cylindrical part430of emitter320includes barb431as illustrated inFIG. 14AandFIG. 14B. Accordingly, barb431can be inserted to a mulching film covering the soil, or barb431can be inserted to a fibrous cultivation bed. Insertion of barb431to the cultivation bed is favorable for specifying the position of dropping of irrigation liquid in the cultivation bed, and for fixing trickle irrigation tube400to the cultivation bed.

Next, discharging of irrigation liquid by emitter320is described.FIG. 19Aillustrates part A ofFIG. 4Bin an enlarged manner in the case where the pressure of the irrigation liquid in tube110is equal to or higher than the first pressure value and lower than the second pressure value,FIG. 19Billustrates part A ofFIG. 4Bin an enlarged manner in the case where the pressure of the irrigation liquid in tube110is equal to or higher than the second pressure value, andFIG. 19Cillustrates part A ofFIG. 4Bin an enlarged manner in the case where the pressure of the irrigation liquid in tube110is reset to a pressure equal to or higher than the first pressure value and lower than the second pressure value.

Supply of irrigation liquid to trickle irrigation tube400is performed in a range where the pressure of the irrigation liquid does not exceed 0.1 MPa for example in view of preventing the damaging of tube110and emitter320. When the irrigation liquid is supplied into tube110, the irrigation liquid reaches flow rate regulation valve458through first cylindrical part410.

When the pressure of the irrigation liquid in tube110is equal to or higher than a first pressure value (for example 0.005 MPa), flow rate regulation valve458is pushed toward second plate part460, and the slit of flow rate regulation valve458expands. In this manner, the irrigation liquid flows into flange part420. Flow rate regulation valve458suppresses inflow of irrigation liquid into flange part420in the case where the pressure of the irrigation liquid is lower than the first pressure value. Thus, irrigation liquid can be supplied to the tube110with high pressure, and therefore the configuration in which emitter320includes flow rate regulation valve458is favorable for forming trickle irrigation tube400having a greater length, for example.

The irrigation liquid having passed through flow rate regulation valve458is supplied to groove455(pressure reduction channel). The pressure of the irrigation liquid flowing through groove455is reduced as a result of pressure loss caused by the shape (zigzag shape) in plan view of groove455. In addition, floating materials in the irrigation liquid are entangled in the turbulent flow generated between the protrusions of groove455and are retained in groove455. In this manner, the floating materials are further removed from the irrigation liquid by groove455.

In addition, since the tip of the protrusion is disposed such that the tip of the protrusion does not exceed the center line of groove455in plan view, a space which is not blocked by the protrusion is formed at the center of groove455while the width of the space is small, and thus the irrigation liquid easily flow through groove455. Accordingly, in addition to the effect of reducing pressure and the effect of removing the floating material, groove455is favorable for allowing irrigation liquid to flow with a greater flow rate.

The irrigation liquid having passed through groove455in which the pressure is reduced and the floating materials are removed is supplied into recess261through groove456. The space of recess454and recess461facing film459is filled with the irrigation liquid, and the irrigation liquid is supplied to hole466(FIG. 19A).

The irrigation liquid having passed through hole466reaches second cylindrical part430through recess463, and is discharged out of tube110through second cylindrical part430.

As the pressure of the irrigation liquid in tube110increases, the flow rate of the irrigation liquid to be received by emitter320from first cylindrical part410increases, and consequently the discharge rate of the irrigation liquid from second cylindrical part430increases.

When the pressure of the irrigation liquid in tube110is equal to or higher than the second pressure value (for example, 0.02 MPa), film459is pushed and is bent by the irrigation liquid introduced into from third cylindrical part440from the inside of tube110as illustrated inFIG. 19B. Thus, the pressure of the irrigation liquid in tube110is transmitted to the rear surface of film459. As a result, film459makes contact with protrusion469of flap467, and pushes flap467.

Flap467and hole466have the same triangular shape in plan view, and the bottom surface of flap plate468is slightly (by an angle obtained by subtracting θ1from θ2) tilted with respect to the opening edge of hole466(tilted part465). Accordingly, since one side of the triangular shape is the fixed end, the distance from the fixed end to the two sides of flap plate468along the bottom surface of flap plate468is greater than the distance from the fixed end to the two sides of hole466along inclined surface465. Thus, flap plate468covers the opening part of hole466, and the peripheral portion of flap plate468of flap467serving as the valve element makes close contact with (sits on) the opening edge of hole466serving as a valve seat. In this manner, flap467functions as the valve element which seals hole466serving as channel for irrigation liquid, and the opening edge of hole466function as the valve seat on which the valve element sits.

However, since groove470is formed on the surface of the opening edge of hole466serving as the valve seat, groove470communicates between the inside of recess461as the channel on the upstream side relative to the valve seat of irrigation liquid and hole466as the channel is the downstream side of the valve seat when flap467serving as the valve element sits on the valve seat. Thus, the irrigation liquid supplied to recess461is supplied to hole466through groove470.

Consequently, the amount of the irrigation liquid which passes through the flow rate control part is restricted to a flow rate which can pass through groove470, and the discharge rate of the irrigation liquid from second cylindrical part430becomes substantially constant. In this manner, emitter320quantitatively discharges the irrigation liquid from tube110supplied with the irrigation liquid.

When hole466is closed by flap467, the pressure in recess461is normally relatively higher than the pressure in hole466. Accordingly, as illustrated inFIG. 19C, even when the pressure of the irrigation liquid in tube110is reduced to a pressure lower than the second pressure value, a pressure difference obtained by subtracting the inner pressure of466from the inner pressure of recess461is a positive pressure, and in addition, in the case where the inner pressure of recess461is greater than the elastic force of returning to the initial position of flap467, flap467keeps closing hole466even when the pressure of the irrigation liquid in tube110is once increased to the second pressure value and thereafter reduced to a value lower than the second pressure value. Thus, the amount of the irrigation liquid passing through the flow rate controlling part is continuously restricted to the flow rates which can pass through groove470.

When the irrigation liquid in recess461sufficiently flows through groove470, the inner pressure of recess461is sufficiently reduced. Then, when the pressure difference is reduced to a value smaller than the elastic force, flap467returns to the initial position with the elastic force, and hole466is opened as illustrated inFIG. 19A. Then, the irrigation liquid in recess461again flows to hole466through the gap between flap467and the opening part of hole466.

As described, emitter320is an emitter for quantitatively discharging irrigation liquid in tube110to outside of tube110, tube110being configured for allowing the irrigation liquid to flow therethrough, emitter320being to be disposed on tube110and including: the intake part for receiving the irrigation liquid in tube110; the pressure reduction channel for allowing the irrigation liquid received from the intake part to flow therethrough while reducing a pressure of the irrigation liquid; the flow rate controlling part for controlling a flow rate of the irrigation liquid supplied from the pressure reduction channel in accordance with a pressure of the irrigation liquid in tube110or in the intake part; and the discharge part which is supplied with the irrigation liquid which has a flow rate controlled by the flow rate controlling part and is to be discharged to the outside of tube110; the flow rate controlling part including: the valve element for opening and closing a channel of the irrigation liquid, the valve seat on which the valve element sits when the valve element closes the channel of the irrigation liquid, film459for pushing the valve element toward the valve seat by being bent under the pressure of the irrigation liquid in tube110or in the intake part such that the valve element sits on the valve seat, and groove470formed on a surface of the valve seat, and configured to communicate between the channel of the irrigation liquid on an upstream side of the valve seat and the channel of the irrigation liquid on a downstream side of the valve seat when the valve element sits on the valve seat. Then, when the pressure of the irrigation liquid in tube110is equal to or higher than a predetermined value, film459pushes the valve element to sit the valve element on the valve seat. Thus, emitter320can stabilize the discharge rate of the irrigation liquid. Further, emitter320can be formed with two injection-molded articles. Therefore, emitter320can further reduce manufacturing cost in comparison with conventional emitters composed of three parts.

In addition, Emitter320includes: first cylindrical part410constituting the intake part, flange part420constituting the pressure reduction channel and the flow rate controlling part, flange part420being connected with one end of first cylindrical part410and extending outward from the one end of first cylindrical part410, and second cylindrical part430constituting the discharge part, the second cylindrical part430being connected on a side opposite to first cylindrical part410of flange part420; emitter320is disposed on the tube by inserting first cylindrical part410into the tube from outside of the tube; flange part420is composed of a combination of first plate part450connected with first cylindrical part410and second plate part460connected with the second cylindrical part430; first plate part450includes film459which is disposed to face a channel of the irrigation liquid on a downstream side of the pressure reduction channel and has a rear surface to which the pressure of the irrigation liquid in the tube or in first cylindrical part410is transmitted; second plate part460includes: the channel on the downstream side of the pressure reduction channel, hole466opening at the channel on the downstream side of the pressure reduction channel to face film459, hole466being communicated with the discharge part, the valve element disposed such that the valve element: forms a gap between the valve element and at least a part of an opening edge of the hole; is allowed to make contact with the opening edge; and, is allowed to be separated from the opening edge; and at least a part of the opening edge of hole466constitutes the valve seat. This configuration is further effective from the viewpoint of forming an emitter to be disposed on the outside of tube110which can achieve the above-mentioned effects.

In addition, an opening shape of hole466includes a linear part; the valve element includes a linear fixed end at the linear part, and is turnable about the fixed end as a turning axis; the valve element has a shape identical to a shape of hole466as viewed along an axis direction (Z direction) of hole466; and a portion where the valve element makes close contact with the valve seat is disposed obliquely to other portion of the opening edge of hole466other than the linear part without making contact with the other portion as viewed along an axis for the turning (in Y direction). This configuration makes it possible to form the flow rate controlling part which operates as described above with one component by injection molding, and is therefore further effective from the view point of reducing manufacture cost.

In addition, film459is disposed independently from first cylindrical part410, and emitter320further includes third cylindrical part440which surrounds film459and is to be inserted into tube110on first cylindrical part410side of first plate part450. In addition, emitter320is disposed to tube110by inserting first cylindrical part410and third cylindrical part440into tube110from the outside of tube110. This configuration makes it possible to form a structure in emitter320for transmitting the pressure of the irrigation liquid in tube110to film459with one component by injection molding including film459, and is therefore further effective from the view point of reducing manufacture cost.

In addition, with the configuration in which the intake part further includes flow rate regulation valve458for expanding the channel for the irrigation liquid when the pressure of the irrigation liquid in tube110is equal to or higher than a predetermined value, the irrigation liquid can be supplied to tube110with a higher pressure, and therefore the configuration is favorable from the standpoint of forming trickle irrigation tube400having a greater length.

In addition, with the configuration in which emitter320is molded with one material having flexibility and film459is integrally molded as a part of emitter320, emitter320can be produced as one component by injection molding, and therefore the configuration is further effective from the standpoint of reducing manufacturing cost.

In addition, the configuration in which hole466is opened and closed with flap467which opens and closes about the fixed end is favorable for increasing the maximum size of the gap between flap467(valve element) and hole466. This configuration is further effective from the view point of suppressing the clogging of the above-mentioned gap. In addition, a channel having a greater size of irrigation liquid and extending to hole466is formed with opened flap467, and thus the irrigation liquid in recess461easily flows to hole466. Therefore, the configuration is further effective from the view point of increasing the discharge rate of the irrigation liquid, and from the view point of increasing the variation of the flow rate of the irrigation liquid with the opening and closing of flap467.

In addition, once flap467is closed, flap467is kept closed until the pressure difference obtained by subtracting the inner pressure of hole466from the inner pressure of recess461is sufficiently reduced (to a value smaller than the above-described elastic force). Accordingly, when the flow rate of the irrigation liquid in the case where the irrigation liquid flows only through groove470is set to a predetermined discharge rate of emitter320, the flow rate of the irrigation liquid significantly varies depending on the opening and closing of flap467as described above, and thus the discharge rate of emitter320quickly returns to the above-mentioned predetermined discharge rate, which is further effective from the viewpoint of quickly achieving the predetermined discharge rate, and from the viewpoint of maintaining the rate for a long period of time.

In addition, since the configuration in which the turning axis of flap467has a linear shape is favorable for performing the opening and closing of flap467(turning) with a smaller force, the configuration is further effective from the viewpoint of precisely setting the predetermined discharge rate of the irrigation liquid in emitter320.

In addition, since the configuration in which each of hole466and flap467has a triangular shape in plan view is favorable for reducing the contact length of the valve element and the valve seat, the configuration is further effective from the viewpoint of preventing displacement of flap467when flap467seals hole466.

When first cylindrical part410and third cylindrical part440is inserted into tube110from the external side of tube110, trickle irrigation tube400including tube110and emitter320disposed to tube110is provided. Since trickle irrigation tube400can quickly achieve a predetermined discharge rate and maintain the rate for a long period of time, irrigation liquid can be discharged substantially at the predetermined discharge rate at all times. Accordingly, trickle irrigation tube400is favorably used for growing of plants which requires further precise discharge of irrigation liquid, for example.

In trickle irrigation tube400, the above-described configurations may be partially changed, or other configurations may be additionally provided as long as the above-described effect is achieved.

For example, second cylindrical part430may not have barb431as illustrated inFIG. 20A, and may be an opening part which opens at the second surface of second plate part460as illustrated inFIG. 20B.

In addition, tube110may be a seamless tube, a tube composed of slender sheet(s) joined together along the longitudinal direction, or a tube having a gap formed at the above-mentioned joining part of the sheets so as to connect the inside and the outside of tube110, or a pipe sandwiched by the sheets at the joining part.

In addition, the first component and the second component may be integrally formed so as to be turnable about a hinge part integrally formed with the first component and the second component. In this case, the number of components of emitter320can be further reduced, that is, emitter320can be produced with one component.

While flap467includes protrusion469having a substantially triangular pyramidal trapezoidal shape with a regular triangular bottom surface and an isosceles triangular top surface, flap467may not be provided with protrusion469as long as bending of film459in accordance with a predetermined value of the pressure of the irrigation liquid in tube110is transmitted. For example, flap467may include an end portion of flap467film459toward protrude rod-shaped protrusion in place of the above-mentioned shape protrusion469. Alternatively, flap467may be provided with the above-mentioned rod-shaped protrusion for film459to push flap467without being provided with protrusion469.

In addition, emitter320may include, in place of third cylindrical part440, a part for transmitting to film770bending of film459in accordance with the pressure of the irrigation liquid in tube110, or, a part capable of directly or indirectly transmitting to the rear surface of film459the pressure of the irrigation liquid in the tube. For example, as illustrated inFIG. 20C, emitter320may include, instead of first cylindrical part410and third cylindrical part440, cylindrical part480which includes the openings of the hole and the recess on the surface of first plate part450.

Further, the first member of emitter320may not be provided with flow rate regulation valve458. For example, as illustrated inFIG. 21AandFIG. 21B, the first member may not be provided with flow rate regulation valve458and third cylindrical part440, tapered hole490which is coupled with first cylindrical part410, and opening part491which opens at the tapered surface of tapered hole490and communicates between tapered hole490and groove455. The irrigation liquid received by first cylindrical part410, while the irrigation liquid transmits pressure to film459, reaches the pressure reduction channel of groove455through opening part491, and further, reaches the flow rate regulating part through the channel of groove456. The flow rate regulating part having the emitter having the above-mentioned structure operates in accordance with the pressure of the irrigation liquid received by the intake part. Thus, the emitter achieves effects of the present embodiment other than effects of flow rate regulation valve458.

This application is entitled to and claims the benefit of Japanese Patent Application No. 2013-272393 filed on Dec. 27, 2013, the disclosure each of which including the specification, drawings and abstract is incorporated herein by reference in its entirety.

INDUSTRIAL APPLICABILITY

According to the present invention, an emitter which can discharge liquid with an appropriate speed by the pressure of the liquid to be discharged can be easily provided. Accordingly, popularization of the above-mentioned emitter in technical fields of trickle irrigations, endurance tests and the like where long-term discharging is required, and further development of the technical fields can be expected.

REFERENCE SIGNS LIST