Dripper for drip irrigation, and drip-irrigation device provided with same

A dripper for drip irrigation according to the present invention comprises a first member and a second member that are formed integrally from a resin material, and includes an inter-member flow passage formed between the members. The first member is provided with a first plate and a pipe that guides an irrigation liquid, which flows in from an inflow part, to the inter-member flow passage. The second member is provided with a second plate and a discharge port. The first member is further provided with a flow regulation valve that regulates the flow of the irrigation liquid, and the second member is provided with a flow-volume control valve that controls the flow volume of the irrigation liquid.

TECHNICAL FIELD

The present invention relates to a drip irrigation dripper and a drip irrigation device including the drip irrigation dripper, and particularly to a drip irrigation dripper and a drip irrigation device including the drip irrigation dripper, which are suitable for growing plants.

BACKGROUND ART

Conventionally, drip irrigation devices have been used to supply irrigation liquids such as water or liquid fertilizer to the plants grown on the soil in the agricultural land, plantation and the like. Regulation of the supply speed of the irrigation liquid with the drip irrigation device enables the saving of the irrigation liquid as well as the management of the growth of the plants.

Such a drip irrigation device includes a drip irrigation dripper. The drip irrigation dripper controls the ejection amount of the irrigation liquid per unit time when ejecting the irrigation liquid having flowed into a flow tube from the water source side (pump side) toward the plants.

One known example of such a drip irrigation dripper is what is called an on-line dripper (see, e.g., PTLS 1 and 2).

On-line drippers are used while being inserted into holes bored in a tube wall (side wall) of polyethylene pipe or into the opening of the end portion of a microtube. On-line drippers are suitable not only for soil culture but also for nutriculture or pot culture when used for greenhouse culture, raising seedling, fruit growing, and the like.

Some on-line drippers have what is called a differential pressure control mechanism (pressure correction function). The drip irrigation dripper is composed of the following three members: an elastic film (e.g., silicone rubber film) such as a diaphragm; an inlet side member and; an outlet side member, as with drip irrigation drippers (emitters) disclosed for example in PTLS 1 and 2. The drip irrigation drippers disclosed in PTLS 1 and 2 have a structure in which the film is sandwiched by the inlet side member and the outlet side member.

The drip irrigation drippers disclosed in PTLS 1 and 2 utilize the operation of the diaphragm (film) in accordance with the liquid pressure of the irrigation liquid having flowed from the inlet to regulate the flow of the irrigation liquid toward a pressure reduction channel on the downstream side of the inlet under low liquid pressure and to control the amount of the outflow of the irrigation liquid from the outlet under high liquid pressure.

More specifically, in the drip irrigation drippers disclosed in PTLS 1 and 2, for example, when the liquid pressure of the irrigation liquid toward the inlet is increased, the diaphragm disposed to block the pressure reduction channel is deflected by the liquid pressure toward the outlet, thereby opening the reduction pressure channel to allow the irrigation liquid to flow into the pressure reduction channel. The irrigation liquid thus having flowed into the pressure reduction channel flows toward the outlet while the pressure of the irrigation liquid is reduced in the pressure reduction channel, and then flows out of the drip irrigation dripper from the outlet. When the liquid pressure toward the inlet is further increased, the amount of the deflection of the diaphragm toward the outlet becomes larger. In association with the larger amount of the deflection of the diaphragm, the sectional size of the channel at the outlet is decreased, and thus the outflow of the irrigation liquid is controlled.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

However, the drip irrigation drippers disclosed in PTLS 1 and 2 have the following problems.

First Problem

In the drip irrigation drippers disclosed in PTLS 1 and 2, when an error occurs upon assembly of the above-mentioned three components, the assembly error greatly affects the performance of the drip irrigation drippers, resulting in variation in the operation of the diaphragm (film), causing the ejection amount or the flow regulation of the irrigation liquid particularly under low liquid pressure to be unstable.

Second Problem

The drip irrigation drippers disclosed in PTLS 1 and 2 require higher material cost when silicone rubber is used for the diaphragm.

Third Problem

The drip irrigation drippers disclosed in PTLS 1 and 2 have difficulty in enhancing the manufacturing efficiency thereof, since it is required to precisely assemble the three components which have been separately manufactured.

Therefore, an object of the present invention is to provide a drip irrigation dripper which makes it possible to stabilize the ejection amount or the flow regulation of the irrigation liquid and to achieve cost reduction and the enhancement of the manufacturing efficiency, and a drip irrigation device including the drip irrigation dripper.

Solution to Problem

The drip irrigation dripper of the present invention is a drip irrigation dripper that performs drip irrigation by controlling an ejection amount when ejecting irrigation liquid flowing from an inflow part out of an ejection port, the drip irrigation dripper including a first member integrally formed of a resin material on the inflow part side, and a second member integrally formed of a resin material on the ejection port side, the first member and the second member being brought into close contact with and fixed to each other, wherein the first member includes a first plate-like part having a first inner surface to be brought into close contact with the second member and a first outer surface opposite to the first inner surface, and a tube part being protruded from the first outer surface of the first plate-like part and having the inflow part being formed, the tube part configured to guide the irrigation liquid flowing from the inflow part to an inter-member channel, and the second member includes a second plate-like part having a second inner surface to be brought into close contact with the first inner surface and a second outer surface opposite to the second inner surface, and the ejection port, the first member further includes a flow regulating valve part that is disposed to be exposed to the first inner surface side to block a downstream end inside the tube part and that regulates a flow of the irrigation liquid guided by the tube part toward the ejection port at a lower limit of a liquid pressure of the irrigation liquid, or the inter-member channel being formed between the first member and the second member, the inter-member channel having surface shapes of close contact surfaces of both the members and being in communication with the inflow part and the ejection port, and the second member further includes a flow rate controlling valve part that controls a flow rate of the irrigation liquid having reached a downstream end of the inter-member channel toward the ejection port.

The flow regulating valve part may include a plate-like first valve element to be exposed to the liquid pressure of the guided irrigation liquid, and a first slit formed on the first valve element to allow the flow of the guided irrigation liquid, wherein the first slit may be formed to have an opening width of zero when the first valve element is not exposed to the liquid pressure, and the first valve element may inhibit the flow by maintaining the opening width of the first slit at zero without deformation of the first valve element when the liquid pressure is less than the lower limit, and the first valve element may allow the flow by expanding the first slit to have an opening width of more than zero through deformation of the first valve element when the liquid pressure is equal to or more than the lower limit.

The first slit may be formed radially to thereby divide the first valve element into a plurality of first valve segments.

The first valve element may be formed to have a shape protruded toward the second member.

The first valve element may be formed such that a central portion of the first valve element is protruded the most, and the first slit may be formed radially around the central portion.

The first valve element may be formed to have a dome shape.

The drip irrigation dripper of the present invention may include an inter-member channel formed between the first member and the second member through a close contact between the first inner surface and the second inner surface to allow the irrigation liquid passing through the flow regulating valve part to flow toward the ejection port.

The inter-member channel may have a pressure reduction channel that allows the irrigation liquid passing through the flow regulating valve part to flow while reducing a pressure of the irrigation liquid.

The second member may include a flow rate controlling valve part that controls a flow rate of the irrigation liquid having reached a downstream end of the inter-member channel toward the ejection port.

The flow rate controlling valve part may include a plate-like second valve element to be exposed to a liquid pressure of the irrigation liquid having reached the plate-like second valve element, and a second slit formed on the second valve element to allow the irrigation liquid having reached the second valve element to flow toward the ejection port, wherein the second slit may be formed to have a predetermined opening width when the second valve element is not exposed to the liquid pressure, and the second valve element may decrease the opening width of the second slit such that an amount of the decrease becomes larger relative to the predetermined opening width as the liquid pressure becomes larger through deformation of the second valve element depending on the liquid pressure.

The flow rate controlling valve part may include a plate-like second valve element to be exposed to a liquid pressure of the irrigation liquid having reached the plate-like second valve element, and a second slit formed on the second valve element to allow the irrigation liquid having reached the second valve element to flow toward the ejection port, wherein the second slit may be formed to have a predetermined opening width when the second valve element is not exposed to the liquid pressure, and the second valve element may decrease the opening width of the second slit such that an amount of the decrease becomes larger relative to the predetermined opening width as the liquid pressure becomes larger through deformation of the second valve element depending on the liquid pressure.

The second valve element may be formed to have a shape protruded toward a side opposite to the ejection port, and the second slit may be formed radially to thereby divide the second valve element into a plurality of second valve segments.

The second valve element may be formed such that a central portion of the second valve element is protruded the most, and the second slit may be formed radially around the central portion.

The second valve element may be formed to have a dome shape.

The inter-member channel may have a pressure reduction channel that allows the irrigation liquid to flow while reducing a pressure of the irrigation liquid.

The first member may include a flow regulating valve part that is disposed to be exposed to the first inner surface side to block a downstream end inside the tube part and that regulates a flow of the irrigation liquid guided by the tube part into the inter-member channel at a lower limit of a liquid pressure of the irrigation liquid.

The flow regulating valve part may include a plate-like first valve element to be exposed to a liquid pressure of the guided irrigation liquid, and a first slit formed on the first valve element to allow the flow of the guided irrigation liquid, wherein the first slit may be formed to have an opening width of zero when the first valve element is not exposed to the liquid pressure, and the first valve element may inhibit the flow by maintaining the opening width of the first slit at zero without deformation of the first valve element when the liquid pressure is less than the lower limit, and the first valve element may allow the flow by expanding the first slit to have an opening width of more than zero through deformation of the first valve element when the liquid pressure is equal to or more than the lower limit.

The inflow part may be formed to have hydrophobicity to thereby inhibit an inflow of the irrigation liquid having a liquid pressure of less than the lower limit.

The inter-member channel may be formed of a space interposed between a recessed surface disposed on one of the first inner surface and the second inner surface, and a planar surface or a recessed surface, facing the recessed surface, disposed on the other one of the first inner surface and the second inner surface.

The ejection port may be formed on the second outer surface or in a second tube part protruded from the second outer surface.

A drip irrigation device of the present invention includes the drip irrigation dripper of the present invention, and an elongated flow tube through which the irrigation liquid flows, wherein the drip irrigation dripper is inserted into a tube wall or an opening of the flow tube through the tube part to thereby allow the irrigation liquid inside the flow tube to flow into a channel of the drip irrigation dripper from the inflow part.

According to the above-described configurations, a drip irrigation dripper having the function of controlling the ejection flow rate of irrigation liquid under high or low liquid pressure can be manufactured with less assembly error with only two components made of a resin material, thus making it possible to stabilize the ejection amount, and to achieve cost reduction due to reduction in the manufacturing cost and the enhancement of the manufacturing efficiency as a result of the removal of a highly precise assembling step. The flow rate controlling valve part or flow regulating valve part can be easily configured, thus making it possible to further reduce the cost. A plurality of second valve segments are deformed toward the center of the radial second slit while reducing an amount of protrusion toward the side opposite to the ejection port due to the liquid pressure, which allows the opening width of the second slit to be narrower, thus enabling the flow rate controlling valve part to be formed into a simple shape suitable for narrowing the opening width of the slit depending on the liquid pressure of the irrigation liquid, making it possible to achieve further suitable flow rate control and further cost reduction. A suitable configuration can be selected for synchronizing the deforming movements of the first or second valve segments by equalizing the size of each valve segment, thus making it possible to achieve further simple flow rate control and further cost reduction. The first valve element or second valve element can be formed into further simple shape, thus making it possible to achieve further cost reduction. The decompression of the irrigation liquid makes it possible to achieve further suitable ejection speed. The drip irrigation dripper provided with a function of regulating the flow of the irrigation liquid under high or low liquid pressure can be manufactured with less assembly error with only two components made of a resin material, thus making it possible to stabilize the flow regulation. The flow regulating valve part can be easily configured, thus making it possible to further reduce the cost. The lower limit of the liquid pressure of the irrigation liquid flowing from the inflow part can be controlled with the hydrophobicity of the inflow part, thus making it possible to properly perform flow regulation under low liquid pressure with a simple configuration. The surface shape for forming the inter-member channel can be produced on both inner surfaces without difficulty in terms of manufacturability, thus making it possible to enhance the manufacturing efficiency and the yield rate. A plurality of first valve segments is deformed toward the second member and in a radiation direction from the center of the first slit (outwardly in a radial direction) due to the liquid pressure, which allows the opening width of the first slit to be wider, thus enabling the flow regulating valve part to be formed into a simple shape suitable for expanding the first slit depending on the liquid pressure of the irrigation liquid, making it possible to achieve further suitable flow regulation and further cost reduction. Securing more contact area between each first valve segment and the irrigation liquid enables the force affecting each valve segment and expanding the first slit to be greater when each valve segment is exposed to the liquid pressure, thus making it possible to securely deform each valve segment and properly expand the first slit even when the irritation liquid has only low pressure. The inner surfaces of two components in close contact with each other can be utilized to efficiently form a channel between the two components. When the ejection port is directly formed on the second outer surface, it is possible to reduce the amount of materials to be used to achieve further cost reduction. On the other hand, when the ejection port is formed in the second tube part, it is possible to easily cope with multiple usage modes such as optimization of the flow direction of the ejected irrigation liquid by connecting a tube to the second tube part, for example. It is possible to stabilize the ejection amount, and to achieve a cost reduction due to reduction in the manufacturing cost and the enhancement of the manufacturing efficiency as a result of the removal of a highly precise assembling step.

Advantageous Effects of Invention

With the present invention, it is possible to stabilize the ejection amount or flow regulation of the irrigation liquid, and to achieve cost reduction and the enhancement of the manufacturing efficiency.

DESCRIPTION OF EMBODIMENTS

In the following, an embodiment of a drip irrigation dripper according to the present invention and a drip irrigation device including the drip irrigation dripper will be described with reference toFIGS. 1 to 17.

FIG. 1is a perspective bird's-eye view illustrating the configuration of a drip irrigation dripper according to the present invention.FIG. 2is a transparent view of the drip irrigation dripper illustrated inFIG. 1.FIG. 3is a perspective upward view of the drip irrigation dripper illustrated inFIG. 1.FIG. 4is a transparent view of the drip irrigation dripper illustrated inFIG. 3.FIG. 5is a plan view of the drip irrigation dripper illustrated inFIG. 1.FIG. 6is a transparent view of the drip irrigation dripper illustrated inFIG. 5.FIG. 7is a bottom view of the drip irrigation dripper illustrated inFIG. 1.FIG. 8is a transparent view of the drip irrigation dripper illustrated inFIG. 7.FIG. 9is a front view of the drip irrigation dripper illustrated inFIG. 1.FIG. 10is a transparent view of the drip irrigation dripper illustrated inFIG. 9.FIG. 11is a schematic sectional view illustrating the configuration of a drip irrigation device according to the present invention.FIG. 12is a perspective upward view of a first member.FIG. 13is a bottom view of the first member.FIG. 14is a perspective bird's-eye view of a second member.FIG. 15is a plan view of the second member.FIGS. 16A and 16Bare enlarged perspective views of a flow regulating valve part.FIGS. 17A and 17Bare enlarged perspective views of a flow rate controlling valve part.

As illustrated inFIG. 11, drip irrigation device2includes elongated tube3as a flow tube through which the irrigation liquid flows, and drip irrigation dripper1inserted into tube3through through-hole31bored in the side wall of tube3.

Drip irrigation dripper1, being inserted into tube3, controls the ejection amount of the irrigation liquid per unit time when the irrigation liquid inside tube3is ejected out of tube3.

It is noted that, while one drip irrigation dripper1and one through-hole31are illustrated inFIG. 11, in actual drip irrigation device2, a plurality of drip irrigation drippers1and a plurality of through-holes31are often disposed along the length of tube3at predetermined intervals.

In addition, inFIG. 11, the right and left sides of the channel in tube3correspond to the upstream side and the downstream side, respectively.

Next, drip irrigation dripper1will be described in detail. As illustrated inFIGS. 1 to 4, 9 and 10, drip irrigation dripper1includes first member4and second member5. Drip irrigation dripper1is assembled by fixing first member4and second member5together in a close contact state. The method of fixing first member4and second member5may be joining by means of adhesion using an adhesive, welding, or the like, or alternatively may be pressure joining by means of pressing. Each of first member4and second member5is integrally formed of a resin material. It is noted that first member4and second member5may be formed of the same resin material, or alternatively may be formed of different resin materials. Examples of the resin material include an inexpensive resin material such as polypropylene. Each of first member4and second member5may be integrally molded by injection molding.

[Specific Configuration of First Member]

As illustrated inFIGS. 1 to 4, 12 and 13, first member4includes first plate-like part41. The shape of first plate-like part41is not particularly limited, and either may be a disc shape, or may be rectangular or other polygonal plate shapes. In the present embodiment, the shape of first plate-like part41is a disc shape

First plate-like part41has first inner surface (lower surface inFIG. 12)411to be brought into close contact with second member5, and first outer surface (top surface inFIG. 1)412opposite to first inner surface411.

First inner surface411and first outer surface412are formed across the thickness of first plate-like part41. First inner surface411and first outer surface412are planes parallel to each other.

As illustrated inFIGS. 12 and 13, first recess4131having a circular shape in a plan view is formed at the center of first inner surface411. As illustrated inFIG. 12, rim part4111of first inner surface411is protruded toward second member5(downward in

<Tube Part and Inflow Part>

As illustrated inFIGS. 1 to 6 and 9 to 12, first member4includes tubular first tube part42. First tube part42is protruded from the center portion of first outer surface412of first plate-like part41toward the side opposite to second member5(upward inFIGS. 1 to 4). First tube part42is formed integrally with first plate-like part41. In addition, the outer peripheral surface of first tube part42is formed to be a cylindrical surface in a predetermined range from the base end portion (lower end portion) to a point before the tip portion (upper end portion) in the protrusion direction. In addition, the outer peripheral surface of first tube part42is formed to be a truncated cone surface swollen outwardly in the radial direction from the cylindrical surface in a predetermined range of the tip portion side. The truncated cone surface functions as a stopper when drip irrigation dripper1is inserted into tube3(seeFIG. 11). However, the outer peripheral surface of the first tube part42is not limited to the cylindrical surface or the truncated cone surface, and may be a square tube surface, a prismoid surface, or the like. The tip portion of first tube part42has inflow port421formed therein as an inflow portion.

As illustrated inFIGS. 2, 4 to 6, 12 and 13, first member4includes flow regulating valve part43. Flow regulating valve part43blocks the downstream end inside first tube part42. In addition, flow regulating valve part43is exposed to first inner surface411side. Flow regulating valve part43regulates the flow of the irrigation liquid guided by first tube part42toward ejection port521(seeFIG. 3). Flow regulating valve part43regulates the flow of the irrigation liquid when the liquid pressure of the irrigation liquid is less than a predetermined lower limit.

Specifically, as illustrated inFIGS. 16A and 16B, flow regulating valve part43has plate-like first valve element431to be exposed to the liquid pressure of the irrigation liquid guided by first tube part42, and first slit432formed on first valve element431to allow the flow of the irrigation liquid.

More specifically, as illustrated inFIGS. 16A and 16B, first valve element431is internally connected to the lower end of inner peripheral surface422of first tube part42. In addition, first valve element431is formed to have the shape of a thin wall dome of which central portion is protruded the most toward second member5(downward) from the lower end of inner peripheral surface422of first tube part42. It is noted that first valve element431is formed on the bottom surface of first recess4131formed in first inner surface411such that the central portion (apex) of first valve element431should not interfere with second member5(seeFIG. 12). In addition, as illustrated inFIGS. 12 and 13, the surface of first valve element431on second member5side (lower surface inFIG. 12) constitutes a portion of a predetermined range around the center on the inner bottom surface of first recess4131.

As illustrated inFIGS. 16A and 16B, first slit432is formed radially (in a cross shape, inFIGS. 16A and 16B) and concentrically with first valve element431. First valve element431is equally divided into a plurality of (four, inFIGS. 16A and 16B) first valve segments431aby first slit432.

As illustrated inFIG. 16A, first slit432is formed such that, when first valve element431is not exposed to the liquid pressure of the irrigation liquid, opening width W1being the width of first slit432is zero. Such a configuration may be obtained by forming first slit432as an incision not having a gap originally.

When the liquid pressure is less than a set lower limit, the rigidity of first valve element431surpasses the liquid pressure, so that first valve element431does not undergo elastic deformation toward second member5. Thus, as illustrated inFIG. 16A, first valve element431can maintain opening width W1of first slit432at zero. In this case, the flow of the irrigation liquid through first slit432is inhibited (blocked). It is noted that the lower limit may be, for example, 0.005 MPa.

On the other hand, when the liquid pressure is equal to or more than the above-described lower limit, first valve element431yields to the liquid pressure to undergo elastic deformation toward second member5. Thus, as illustrated inFIG. 16B, first valve element431expands first slit432such that opening width W1is greater than zero to allow the flow of the irrigation liquid through first slit432.

As illustrated inFIGS. 12 and 13, first member4has inter-member channel part413of a recessed surface formed in first inner surface411of first plate-like part41.

As illustrated inFIG. 13, inter-member channel part413has first recess4131described above, pressure reduction channel part4132continuously connected to the terminal end (downstream end) of first recess4131, and rectangular second recess4133continuously connected to the terminal end of pressure reduction channel part4132.

Specifically, as illustrated inFIG. 13, pressure reduction channel part4132is formed substantially U-shape. Pressure reduction channel part4132extends outwardly in a serpentine manner in the radial direction of first inner surface411from a part of the circumference of first recess4131(left end portion inFIG. 13), and then turns back before rim part4111of first inner surface411to return to the vicinity of first recess4131without serpentine.

Inter-member channel part413forms inter-member channel7(seeFIG. 2), being in communication with inflow port421and ejection port521, together with second member5. Out of inter-member channel7, pressure reduction channel part4132being a part of inter-member channel7forms, together with second member5, pressure reduction channel71that allows the irrigation liquid having passed through flow regulating valve part43to flow toward ejection port521while reducing the pressure of the irrigation liquid.

It is noted that the shape of pressure reduction channel part4132is not limited to the shape illustrated inFIGS. 12 and 13. In addition, a plurality of pressure reduction channel parts4132may be provided.

[Specific Configuration of Second Member]

As illustrated inFIGS. 1 to 4, 14 and 15, second member5has disc-shaped second plate-like part51being concentric with and having the same diameter as that of first plate-like part41. However, the shape of the second plate-like part51does not need to be limited to a disc shape, and may be, for example, rectangular or other polygonal plate shapes.

Second plate-like part51has second inner surface (top surface inFIG. 14)511to be brought into close contact with first inner surface411of first plate-like part41, and second outer surface (lower surface inFIG. 3)512opposite to second inner surface511.

Second inner surface511and second outer surface512are disposed across the thickness of second plate-like part51. Second inner surface511and second outer surface512are planes parallel to each other.

In addition, second inner surface511and first inner surface411are brought into close contact with each other, thereby to form inter-member channel7, formed by surface shapes of close contact surfaces411and511, between first member4and second member5. That is, inter-member channel7is formed of a space interposed between first recess4131(recessed surface) and second inner surface511(planar surface), a space interposed between pressure reduction channel part4132(recessed surface) and second inner surface511(planar surface) (i.e., pressure reduction channel71), and a space interposed between second recess4133(recessed surface) and second inner surface511(planar surface) as well as third recess5112(recessed surface) to be described later.

It is noted that second inner surface511may be joined to first inner surface411.

As for other components, rim part5111of second inner surface511is recessed by the same dimension as the protrusion dimension of rim part4111of first inner surface411(seeFIG. 10). It is also possible to use rim parts4111and5111for positioning first member4and second member5. In addition, as illustrated inFIG. 14, third recess5112having a circular shape in a plan view is formed at a position deviated outwardly in a radial direction from the center of second inner surface511. Third recess5112faces second recess4133when first member4and second member5are fixed together.

<Second Tube Part and Ejection Port>

As illustrated inFIGS. 1 to 4, and 7 to 10, second member5has tubular second tube part52. As illustrated inFIG. 3, second tube part52is protruded toward the side opposite to first member4(downward inFIG. 3) from second outer surface512of second plate-like part51, and is formed integrally with second plate-like part51.

The outer peripheral surface of second tube part52is formed to be a cylindrical surface in a predetermined range from the base end portion (upper end portion) to a point before the tip portion (lower end portion) in the protrusion direction. In addition, the outer peripheral surface of second tube part52is formed to be a truncated cone surface swollen outwardly in the radial direction beyond the cylindrical surface in a predetermined range of the tip portion side. However, the outer peripheral surface of second tube part52does not need to be limited to the cylindrical surface or the truncated cone surface, and may be a square tube surface, a prismoid surface, or the like.

Ejection port521that opens circularly is formed in the tip portion of second tube part52.

As illustrated inFIGS. 4, 7, 8 and 10, second member5includes flow rate controlling valve part53. Flow rate controlling valve part53is disposed at the downstream end of inter-member channel7to partially block the upstream end inside second tube part52. Flow rate controlling valve part53controls the flow rate of the irrigation liquid having reached the downstream end of inter-member channel7toward ejection port521.

Specifically, as illustrated inFIGS. 17A and 17B, flow rate controlling valve part53has plate-like second valve element531to be exposed to the liquid pressure of the irrigation liquid having reached the downstream end of inter-member channel7, and second slit532formed on second valve element531to allow the irrigation liquid to flow toward ejection port521.

More specifically, as illustrated inFIGS. 17A and 17B, second valve element531is formed at a position from second inner surface511to third recess5112(seeFIGS. 14 and 15) to have the shape of a thin wall dome of which central portion is protruded the most toward the side opposite to ejection port521(upward). In addition, as illustrated inFIGS. 17A and 17B, second slit532is formed radially (in a cross shape, inFIGS. 17A and 17B) around the central portion of second valve element531. Second valve element531is equally divided into a plurality of (four, inFIGS. 17A and 17B) second valve segments531aby second slit532.

As illustrated inFIG. 17A, second slit532is formed such that, when not exposed to the liquid pressure of the irrigation liquid, opening width W2of second slit532is predetermined opening width A greater than zero.

In addition, second valve element531undergoes deformation toward ejection port521(downward, inFIGS. 17A and 17B) depending on the liquid pressure, while being exposed to the liquid pressure of the irrigation liquid. Thus, as illustrated inFIG. 17B, second valve element531decreases opening width W2of second slit532relative to predetermined opening width A such that the amount of the decrease becomes larger, as the liquid pressure becomes larger. However, there may be a lower limit of the irrigation liquid for initiating the deformation of second valve element531.

[Principal Operation and Effect of Present Embodiment]

According to the present embodiment, the irrigation liquid inside tube3flows into first tube part42from inflow port421, passes through the channel inside tube part42, and reaches flow regulating valve part43.

When the liquid pressure of the irrigation liquid having reached flow regulating valve part43does not amount to a set lower limit, the rigidity of first valve element431in flow regulating valve part43surpasses the liquid pressure, and thus first valve element431does not undergo elastic deformation. Consequently, opening width W1of first slit432is maintained at zero (i.e., equivalent to the state where the liquid pressure has no influence), to inhibit the inflow of the irrigation liquid into inter-member channel7.

On the other hand, when the liquid pressure of the irrigation liquid having reached flow regulating valve part43amounts to the set lower limit, the liquid pressure surpasses the rigidity of first valve element431, and thus first valve element431(each first valve segment431a) elastically deforms toward second member5(in other words, toward inter-member channel7). Consequently, first slit432is expanded such that opening width W1is increased from zero to a value in accordance with the liquid pressure, to allow the inflow of the irrigation liquid into inter-member channel7.

In this manner, the irrigation liquid having flowed from flow regulating valve part43undergoes pressure reduction by pressure reduction channel71in the course of passing through inter-member channel7, and then reaches flow rate controlling valve part53.

Second valve element531of flow rate controlling valve part53elastically deforms toward ejection port521depending on the liquid pressure of the liquid having reached second valve element531. Thus, second valve element531decreases opening width W2of second slit532, relative to opening width W2in a state where the liquid pressure has no influence, such that the amount of the decrease becomes larger, as the liquid pressure becomes larger. It is noted that a suitable lower limit in accordance with the wall thickness of second valve element531, the width of slit532, and the like may be set as a lower limit of the internal liquid pressure for the elastic deformation of second valve element531.

Thus, the irrigation liquid passing through the channel in second slit532and moving toward ejection port521all at once is regulated in terms of flow rate due to the decrease of opening width W2in association with the elastic deformation of second valve element531.

Two cases will now be discussed in which the liquid pressure of the irrigation liquid flowing into drip irrigation dripper1is relatively high or low. Causes of the occurrence of such two cases are: the position on tube3at which drip irrigation dripper1is attached (whether near to or distant from a pump); the performance of the pump itself (whether high pressure pump or low pressure pump), a change in the performance of the pump itself over time; and so forth.

First, when the irrigation liquid has high pressure, the amount of the inflow of the irrigation liquid into the channel of drip irrigation dripper1becomes relatively large. At the same time, relatively large amount of deformation of flow rate controlling valve part53also causes the flow rate regulated by flow rate controlling valve part53to be relatively large. Therefore, there is no such case where the ejection amount of the irrigation liquid from ejection port521becomes excessively large.

On the other hand, when the irrigation liquid has low pressure, the amount of the inflow of the irrigation liquid into the channel of drip irrigation dripper1becomes relatively small. At the same time, relatively small amount of deformation of flow rate controlling valve part53also causes the flow rate regulated by flow rate controlling valve part53to be relatively small. Therefore, there is no such case where the ejection amount of the irrigation liquid from ejection port521becomes excessively small.

Thus, drip irrigation dripper1can favorably control the ejection amount of the irrigation liquid from ejection port521to have less variation (to limit variation to 5 to 10%, for example), irrespective of the liquid pressure at the time of inflow.

According to the present embodiment, drip irrigation dripper1provided with functions of controlling the ejection flow rate of and regulating the flow of the irrigation liquid under high or low liquid pressure can be manufactured with less assembly error only with first member4and second member5made of a resin material. Therefore, drip irrigation dripper1is capable of stabilizing the ejection amount, and makes it possible to achieve cost reduction due to reduction in the manufacturing cost and the enhancement of the manufacturing efficiency as a result of the removal of a highly precise assembling step. In particular, drip irrigation dripper1according to the present embodiment is highly advantageous in terms of cost and manufacturing efficiency, compared with the case of incorporating a diaphragm made of an expensive material such as silicone rubber as a separate component.

In addition, each first valve segment431areceives the liquid pressure from above, to thereby allow first valve element431of flow regulating valve part43to deflect downwardly and outwardly utilizing the elasticity of a resin material, in such a manner that the tips of the respective first valve segments431aare spaced apart from each other. Thus, first valve segment431ais formed into a suitable shape for expanding first slit432by receiving the liquid pressure efficiently, and therefore the inflow regulation can be performed more properly.

In addition, as for second valve element531of flow rate controlling valve part53, each second valve segment531areceives the liquid pressure of the irrigation liquid from the side opposite to ejection port521(from above, inFIGS. 17A and 17B), to thereby allow second valve element531to deflect toward ejection port521(downwardly, inFIGS. 17A and 17B) utilizing the elasticity of a resin material, in such a manner that the protrusion amount is decreased and that the tips of the respective second valve segments531aare made to be closer to each other. Thus, second valve element531is formed into a suitable shape for narrowing opening width W2of second slit532by receiving the liquid pressure efficiently, and therefore the flow rate toward ejection port521can be controlled more properly.

It is noted that the present invention is not limited to the above-described embodiments, and may be variously modified insofar as the features of the present invention are not impaired.

For example, first valve element431may have a shape other than the domed shape (e.g., pyramidal shape or flat shape) as necessary.

FIG. 18is a perspective bird's-eye view illustrating the configuration of a drip irrigation device according to a first modification. As illustrated inFIG. 18, second tube part52may be formed shorter than that in the configuration ofFIG. 1.

FIG. 19is a perspective upward view illustrating the configuration of a drip irrigation device according to a second modification. As illustrated inFIG. 19, ejection port521may be formed on second outer surface512to thereby achieve the reduction in the amount of materials to be used.

FIG. 20is a plan view illustrating the configuration of a drip irrigation device according to a third modification. Instead of forming inter-member channel part413on first inner surface411as illustrated inFIG. 13, similar component413′ may be provided on second inner surface511as illustrated inFIG. 20.

In addition, instead of providing the above-mentioned flow regulating valve part43, a hydrophobic inflow part may be provided to thereby inhibit the inflow of the irrigation liquid having a liquid pressure of less than a lower limit.

FIG. 21is a schematic configuration diagram illustrating the configuration of a drip irrigation device according to a fourth modification (enlarged sectional view of inflow part421′).

As illustrated inFIG. 21, inflow part421′ has substrate part4211′ orthogonal to the longitudinal direction of first tube part42, and a plurality of circular pore-like inflow ports4212′ penetrating substrate part4211′ vertically (in other words, parallel to the longitudinal direction of first tube part42).

Inflow part421′ is provided with a low-pressure stop filter function for not allowing irrigation liquid having a liquid pressure of less than a lower limit (e.g., 0.005 MPa) to flow into first tube part42.

There are several possible means to embody the low-pressure stop filter function.

For example, when polypropylene is used as a material for drip irrigation dripper1, the low-pressure stop filter function can be easily imparted to the entire surface of inflow part421′, since polypropylene itself is highly hydrophobic material with a low surface energy.

Other than that, when hydrophobic coating such as fluorine coating by means of a fluorine coating agent is applied to the top surface of substrate part4211′ and, as necessary, to the inner peripheral surface of inflow port4212to reduce the surface energy, the low-pressure stop filter function can be imparted to inflow part221locally without limiting the material for drip irrigation dripper1.

In either case of depending on a material or applying a surface coating as described above, hydrophobicity may be reinforced by forming an irregular shape on the hydrophobic surface, as necessary.

This application is entitled to and claims the benefit of Japanese Patent Application No. 2012-274556 filed on Dec. 17, 2012, and Japanese Patent Application No. 2012-278354 filed on Dec. 20, 2012, the disclosure of which including the specification, drawings and abstract are incorporated herein by reference in their entirety.

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