Patent Description:
Drip irrigation is a watering method that utilizes pressurized water sources and drips water along a distribution pipe in a controlled manner.

Drip irrigation systems are considered to be more efficient than surface irrigation systems that typically convey water to fields in open canals or low pressure pipelines. Surface irrigation systems require smaller investment and lower energy costs, and these systems typically employ high discharge at the inlet in order to irrigate efficiently and uniformly across a field so that water will reach the end of the field.

<CIT> discloses a distribution pipe made of thin-walled sleeve that is collapsible when empty and that includes holes in its walls Branch tubes equipped with low-pressure drip emitters are connected to the holes of the distribution pipe by connectors. The sleeve material is opaque and reflecting the solar radiation so that the growth of microorganisms and algae is suppressed, the pipe is not heated more than <NUM> above the ambient air temperature. <CIT> discloses a water dripper for irrigation. The dripper is installed on a tube. The dripper includes a body, a body lid, and a dripper core. Water enters through an inlet opening that is formed in the body lid, and that is initially sealed by core. The water pressure in tube deforms core until there a slit between the core and the lid. The water flows through the formed slit into an effluent groove formed on the core. From the groove the water continues into an outlet hole at the top part of the dripper, through which it is sprayed out of the tube.

In the present invention there is provided a water irrigation dripper according to claim <NUM> and the method for irrigation according to claim <NUM>, the preferred embodiments are provided in dependent claims <NUM>-<NUM>, <NUM>.

According to some embodiments a length of the water pathway is from about <NUM> to about <NUM>. According to some embodiments of the invention the length of the water pathway is from about <NUM> to about <NUM>.

According to some embodiments a diameter of the internal element is from about <NUM> to about <NUM>. According to some embodiments of the invention the diameter of the internal element is from about <NUM> to about <NUM>.

According to some embodiments a hydraulic diameter of the water pathway is from about <NUM> to about <NUM>. According to some embodiments of the invention a hydraulic diameter of the water pathway of from about <NUM> to about <NUM>.

According to some embodiments there is a plurality of water inlets at a density of from about <NUM> water inlet to about <NUM> water inlets per square centimeter.

According to some embodiments the water pathway at least partially surrounds the internal element.

According to some embodiments the water inlet has a generally elliptic shape.

According to some embodiments the walls of the water inlet are generally perpendicular to an outer surface of the external hollow element.

According to some embodiments the water irrigation dripper comprises a water filter at one or more of the water inlets.

According to some embodiments the water irrigation dripper comprises at least one additional water inlet, oriented diagonally with respect to a normal to an outer surface of the external hollow element.

According to the present invention there is provided an irrigation system according to claim <NUM>.

It is appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale.

The present invention, in some embodiments thereof, relates to irrigation and, more particularly, to method and system for irrigation at low water pressure.

For purposes of better understanding some embodiments of the present invention, as illustrated in <FIG> of the drawings, reference is first made to the construction and operation of an irrigation system and a dripper as illustrated in <FIG> and <FIG>.

<FIG> illustrates an irrigation system <NUM> that includes a water supply <NUM>, a pump <NUM> for pumping water from the water supply <NUM> to a plurality of conduits <NUM>, thereby resulting in high-pressure water flow in the plurality of conduits <NUM>. A plurality of drippers <NUM> is attached to the plurality of conduits <NUM>, for decreasing the velocity of water flowing throughout the conduits <NUM> and for discharging the water to the ground at a controlled rate.

<FIG> illustrates a dripper <NUM> having a generally zigzag shaped water pathway <NUM>, comprising alternately arranged protrusions, decreases the velocity of the water passing therethrough. Dripper <NUM> also includes a water inlet <NUM> through which water enters the dripper, and a water outlet <NUM> through which water flows out of the pathway to the ground. Dripper <NUM> also includes a filter (not shown), for preventing particles from entering dripper <NUM> and clogging it. The zigzag-shaped pathway <NUM> creates turbulence, which, in turn, causes energy loss. The energy loss is controlled by the structure and size of the water pathway <NUM>.

The inventors found that traditional drippers may clog when particles accumulate therein, and that this requires constant supervision and inspection of the irrigation field and may increase the operating expenditure.

The inventors further found that reducing the operating pressure can reduce or eliminate the need for a pump, which, in turn, can reduce energy costs.

<FIG> and <FIG> are schematic illustrations of an irrigation system <NUM>, in accordance with some embodiments of the present invention. In various exemplary embodiments of the invention irrigation system <NUM> operates at a low water pressure, e.g., less than <NUM> bar, more preferably from about <NUM> mbar to about <NUM> mbar, more preferably from about <NUM> mbar to about <NUM> mbar, more preferably from about <NUM> mbar to about <NUM> mbar, more preferably from about <NUM> mbar to about <NUM> mbar, more preferably from about <NUM> mbar to about <NUM> mbar, more preferably from about <NUM> mbar to about <NUM> mbar e.g., <NUM> mbar. Irrigation system <NUM> comprises a water supply system <NUM>, which preferably supplies water at low pressure. Irrigation system <NUM> comprises an irrigation pipe <NUM> and one or more drippers <NUM>. While <FIG> and <FIG> show irrigation pipe <NUM> in a generally horizontal orientation. System <NUM> can optionally and preferably be connected through a connector and/or valve <NUM>. optionally and preferably to one or more of water distribution conduits <NUM>. Alternatively or additionally, system <NUM> can be connected to one or more of a water reservoir, a water tank, a water container or a well.

In some embodiments, system <NUM> comprises a water pump <NUM> that delivers water to system <NUM> or water distribution conduits <NUM> or irrigation pipe <NUM>, as desired. System <NUM> optionally and preferably comprises one or more pressure sensors <NUM> that measure water pressure in irrigation pipe <NUM>. System <NUM> can further comprise a control system <NUM> for controlling the flow rate of the water supplied to irrigation pipe <NUM>. Control system <NUM> can include a circuit that is configured to transmit control signals to pump <NUM> or connector and/or valve <NUM> thereby to control the flow rate in pipe <NUM>. Optionally and preferably control system <NUM> receives sensing signals from sensors <NUM> and transmits the controls responsively to these sensing signals, so as to maintain the aforementioned water pressure in irrigation pipe <NUM>.

Drippers <NUM> can be attached to, integrated in, or located in the interior of, irrigation pipe <NUM>. In operation, drippers <NUM> discharge water through at least one water outlet <NUM>, to provide a flow of water, for example, to soil, ground, or furrow. Outlet <NUM> of dripper <NUM> can optionally and preferably be adjacent to a hole <NUM> in pipe <NUM>.

Irrigation pipe <NUM> can be made of any suitable material known in the art to operate normally to withstand pressure of at least <NUM> bars, to withstand accidental pressures as a result of loads generated, for example, by overridden wheels of a vehicle, and/or to withstand weather conditions, such as rain, or high temperatures typically caused from heat generated by the sun. For example, suitable materials may be polyethylene, polypropylene. polyvinylchloride and other thermoplastic materials. Typically, irrigation pipe <NUM> has a diameter of from about <NUM> and to about <NUM>, and length of from about <NUM> to about <NUM>.

Drippers <NUM> are disposed along irrigation pipe <NUM>. A typical distance between two adjacent drippers along pipe <NUM> is, without limitation, from about <NUM> to about <NUM>.

Drippers <NUM> can be embodied in more than one way. In the representative example shown in <FIG>, one or more, preferably each of, drippers <NUM> is fixed on the inner wall of irrigation pipe <NUM>, and may comprise one or more water inlet <NUM> through which the water enters the dripper <NUM>, one water outlet <NUM> through which the water exits the dripper <NUM>, and a water pathway <NUM> through which the water flows from the inlet <NUM> to the outlet <NUM>. For example, a typical dripper <NUM> may include from about <NUM> to about <NUM> dripper inlets, and <NUM> dripper outlet.

<FIG> illustrates dripper <NUM> according to another embodiment. In this embodiment, dripper <NUM> comprises a compact housing <NUM> made of a sturdy and non-corrosive material. The top surface <NUM> of dripper <NUM> defines two sets of inlets, each including one or more openings extending through the top surface <NUM>. The inlets are exposed to the irrigation water flowing through the inside of the irrigation tube.

The first inlet <NUM> preferably includes three openings. Water flowing into the first inlet <NUM> proceeds through the body of dripper <NUM> to an outlet (not shown). In traveling through dripper <NUM> to the outlet, water pressure is reduced and water flow is reduced to a trickle or drip flow rate. The three openings are preferably sufficiently small in diameter to perform a filter function for water flowing through the first inlet <NUM>, for example, to filter out debris or grit that might otherwise clog the interior of dripper <NUM>. The openings making up the first inlet <NUM> are optionally and preferably spaced in a triangular pattern to allow water to uniformly impact interior surfaces of dripper <NUM>. Although three equally spaced openings are shown in the preferred embodiment, other numbers and arrangements of openings may be utilized to form the first inlet <NUM>.

The second inlet <NUM> preferably including two openings spaced along a center axis bisecting the length of dripper <NUM>. Water flowing into the second inlet <NUM> optionally and preferably does not proceed through the body of dripper <NUM> but, instead, serves a pressure compensation function. Water flowing into the second inlet <NUM> accumulates in a chamber in the interior of dripper <NUM>, applying pressure to the chamber in an amount substantially equivalent to the pressure in the irrigation tube. Because water flowing through the second inlet <NUM> does not flow through dripper <NUM>, the openings of the second inlet <NUM> need not filter the inflowing water and the openings need not be small in diameter. Although two openings are shown in the preferred embodiment, as seen in <FIG>, other numbers and arrangements of openings may be utilized to form the second inlet <NUM>.

<FIG> illustrate dripper <NUM> according to another embodiment. In this embodiment, dripper <NUM> comprises a compact housing which can be conveniently and economically formed from assembled plastic molded housing components. The housing includes a generally cup-shaped base <NUM> adapted for assembly with a cap <NUM> to form a substantially enclosed housing interior. In general terms, the flow channel <NUM> is defined by a channel pattern <NUM> formed in the base <NUM>, in cooperative relation with a resilient and flexible elastomeric valve member <NUM>. Water is supplied to the flow channel <NUM> via a water inlet <NUM> formed by the cap <NUM>. and water is discharged from the flow channel through the discharge outlet <NUM> formed in the base <NUM>. The geometry of the channel pattern <NUM> cooperates with the valve member <NUM> to define the three dimensional flow channel <NUM> for improved pressure drop between the inlet <NUM> and the outlet <NUM>.

Housing base <NUM> has an upwardly open, generally cup-shaped construction including a circular bottom or floor surface <NUM> joined at the perimeter thereof to a cylindrical upstanding outer wall <NUM>. The channel pattern <NUM> is formed on the floor <NUM> with a generally circular configuration arranged about the outlet <NUM> which may include a short downwardly projecting hollow stem <NUM> for press-fit attachment to discharge tubing (not shown), if desired. A plurality of spacer posts <NUM> are also formed on the base <NUM> to project upwardly from the floor <NUM> at the floor perimeter and terminate with upper ends disposed above the channel pattern <NUM>, but below the upper edge of the outer wall <NUM>.

The valve member <NUM> comprises a resilient disk having a size and shape to fit into the housing base <NUM>, with an outer margin of the valve member <NUM> fitting within the spacer posts <NUM>. The housing cap <NUM> is then assembled with the base <NUM> by press-fit mounting of the disk-shaped cap into the open end of the base, to seat the cap <NUM> against the upper ends of the spacer posts <NUM>. The cap <NUM> can be securely connected to the base <NUM> in a sealed manner by use of a suitable adhesive, or by ultrasonic welding or the like. When assembled, the housing base <NUM> and cap <NUM> defined an inlet chamber <NUM> (<FIG>) within which the valve member <NUM> is retained with at least some floating movement in a position aligned over the channel pattern <NUM>. The water inlet <NUM> is formed in the cap <NUM> and is typically associated with an inlet stem <NUM> which may include a barbed construction for press-on puncture type attachment to the water supply hose <NUM>.

From flow channel <NUM>, the water enters the centrally located discharge chamber having a raised circular boss <NUM> projecting upwardly from the floor <NUM> of the housing base <NUM> to engage the valve member <NUM>. The boss <NUM> has an upwardly open discharge regulating groove <NUM> formed therein, for discharge flow of the water from the outlet chamber to the water outlet <NUM>.

<FIG> illustrate dripper <NUM> according to another embodiment. The dripper <NUM> may be a molded plastic body that may be inserted into thin walled drip tape <NUM>, or any other type of water conduit such as an extruded hose, at regularly spaced intervals during or immediately following extrusion of the drip tape. Each dripper <NUM> may have a single outlet that may be positioned at an opening <NUM> that is cut or pre-formed in the wall of the drip tape during production. Water in thin walled drip tape <NUM> may enter the dripper <NUM> by passing through a filter at the dripper's sides or perimeter <NUM>. Because the filter area is in the dripper's sides or perimeter, the dripper <NUM> can provide a filter of large area relative to the size or thickness of the dripper <NUM>. For example, the dripper <NUM> in a preferred embodiment may have a thickness of about <NUM>, and a filter area of at least about <NUM><NUM>.

In one embodiment, filtered water then passes through labyrinth <NUM> where water pressure is reduced. For example, water pressure may be reduced from the line pressure in the drip tape (e.g., <NUM> psi) to a substantially lower pressure. Water at the reduced pressure then may flow through outlet hole <NUM> near the dripper's first or outer face <NUM> welded or adhered to the drip tape wall.

In one embodiment, the dripper <NUM> is pressure regulated using diaphragm <NUM> at or adjacent the dripper's second or inner face <NUM>. Water pressure in the drip tape acts against the diaphragm to regulate the dripper's flow rate as water pressure changes within the water conduit.

Dripper <NUM> may include three parts, two body members <NUM> and <NUM>, and elastomeric diaphragm <NUM>. The dripper's first or outer face <NUM> may have one or more walls or surfaces that are welded, adhered to or otherwise bonded to the drip tape inner wall. The dripper <NUM> has a second or inner face <NUM> that may project inwardly toward the interior of the drip tape. The thickness of the dripper <NUM> between the first or outer face and the second or inner face is preferably less than about <NUM>, and most preferably less than about <NUM>. The filter area of the dripper <NUM> is entirely on the sides <NUM> or periphery of the dripper <NUM>, between the dripper's outer face <NUM> and inner face <NUM>.

In one embodiment, the filter area may be configured as a plurality of slots <NUM> through the sides of the dripper <NUM> which provide filtering inlets or passages for water in the drip tape to enter into the dripper <NUM>. Each slot <NUM> through the dripper's side walls may have dimensions that are small enough to block particles or debris from passing through the slot to the interior of the dripper <NUM>, while allowing a desired flow rate of water from the drip line into the interior of the dripper <NUM>.

For example, in one embodiment, the dripper <NUM> may be generally disc shaped, and each slot <NUM> may extend radially through the dripper's cylindrical side walls <NUM>, from the perimeter or outer surface to the interior of the dripper <NUM>. Dripper <NUM> may have <NUM> radial slots, each slot having a width of less than about <NUM>, and most preferably having a width of less than about <NUM>. The radial thickness of the dripper's side walls may be between about <NUM> and about <NUM>. The dripper's radius may be between about <NUM> and about <NUM>, and the dripper's outer circumference may be between about <NUM> and about <NUM>.

In one embodiment, the second or inner face <NUM> of the dripper <NUM> may have an opening <NUM>. Diaphragm <NUM> may be an elastic bladder that is positioned between body members <NUM> and <NUM>, while the diaphragm is directly exposed on one side to the water pressure within the drip tape or other water conduit where the dripper <NUM> is mounted. For example, the diaphragm may have a thickness of about <NUM> to about <NUM>, and a surface which is large enough to cover both pressure regulating chamber <NUM> and labyrinth <NUM> which is formed in second body member <NUM> on surface <NUM>.

In one embodiment, the diaphragm may be exposed to line pressure in the drip tape which may enter through opening <NUM> and directly act against the diaphragm, causing the diaphragm to flex as the water pressure at the diaphragm on the other side is decreased. If water pressure in the drip tape increases, the diaphragm may flex radially toward outlet <NUM> and away from the dripper's second or inner face, reducing the outlet flow from the dripper <NUM>.

In one embodiment, water acting against the diaphragm while passing through opening <NUM> does not also pass through a filter. Instead, the filter may be an array of slots <NUM> in the dripper's cylindrical side walls <NUM>, and are dedicated only for water entering the dripper's pressure reducing area, or labyrinth <NUM>.

In one embodiment, diaphragm <NUM> may be held in place by sandwiching outer portions of the diaphragm between first body member <NUM> and second body member <NUM> of the dripper <NUM>. The first and second body members may be engaged together with a snap or press fit. For example, the second member may be inserted into the first member, and may be held in place by shoulders <NUM> that extend inwardly from the dripper's side walls <NUM>. The inwardly facing shoulders may capture and hold the second member in place because the dimensions of the second member's outer rim or perimeter <NUM> may be slightly larger than the dimensions of shoulders <NUM>. Diaphragm <NUM> may be held between surface <NUM> of the first member and one or more walls <NUM>, <NUM> of the second member. Optionally, the shoulders and outer rim or perimeter may be tapered to facilitate ease of assembly. Additionally, portions of the diaphragm that are radially outside of opening <NUM> may be compressed axially by a tight or sealing interfit between the first and second body members.

In one embodiment, water entering the dripper <NUM> through the filter area in the dripper's sides may be collected in manifold flow channel <NUM> inside the filter area. For example, the manifold flow channel may be a passage radially within the filter area on the dripper's side walls <NUM>, and may be enclosed by the drip tape wall, surface <NUM>, and wall <NUM> that circumscribe exit pool <NUM>.

In various exemplary embodiments of the invention irrigation pipe <NUM> is arranged to compensate pressure losses in the drippers along the irrigation pipe. In operation, water supply system <NUM> delivers water to pipe <NUM>, optionally and preferably at a highest level of pipe <NUM>.

It was found by the Inventors that this results in a generally high water flow rate, and also maintains a generally uniform flow rate in all drippers <NUM>.

In some embodiments control system <NUM> ensures that water supply system <NUM> delivers the water to pipe <NUM> at a pressure of at most about <NUM> H<NUM>O (e.g., from about <NUM> to about <NUM> H<NUM>O), or at most <NUM> H<NUM>O (e.g., from about <NUM> to about80 cm H<NUM>O), or at most <NUM> H<NUM>O (e.g., from about <NUM> to about <NUM> H<NUM>O), or at most <NUM> H<NUM>O (e.g., from about <NUM> to about <NUM> H<NUM>O), or at most <NUM> H<NUM>O (e.g., from about <NUM> to about <NUM> H<NUM>O), and further or at most <NUM> H<NUM>O (e.g., from about <NUM> to about <NUM> H<NUM>O). For example, when supply system <NUM> is a pump and/or comprises a controllable valve (not shown), control system <NUM> can controls the pump or valve to deliver the preferred pressure. Alternatively, water supply system <NUM> can be configured to the deliver the water at the aforementioned pressure without a control system (e.g., by a judicious selection of the outlet diameter and/or pressure within the water supply system <NUM>).

Drip irrigation systems involve investment costs and power consumption in high pressure (energy) and filtration systems to work efficiently. Surface irrigation systems typically employ high discharge at a water inlet in order to irrigate efficiently and uniformly using surface irrigation so that water will reach an end of the field. It was found by the inventors of the present invention that reduction of water amount by a steeper slope field may cause runoff, erosion and soil degradation.

Drip irrigation systems provide higher water uniformity across a field than surface irrigation due to reduced runoff and leaching, however, it was realized by the inventors of the present invention that the high pressure requirement causes high energy costs and high investment costs in filters, pumps, pressure regulators, and materials of irrigation pipe that can withstand high pressure. It was realized by the inventors of the present invention that drip irrigation systems that work at pressures between <NUM> to <NUM> bar and cannot be applied in large commercial fields. A criterion for discharge variation in an irrigated field is typically <NUM>% or less.

The inventors found that an irrigation system comprising an irrigation pipe that may be inclined at a varying slope, may be selected such that a water discharge along a length of the inclined irrigation pipe varies by no more than about <NUM>%, or no more than <NUM>%, or no more than <NUM>%, or no more than <NUM>%, or no more than <NUM>%, or no more than <NUM>%, or no more than <NUM>%.

As used herein, "water discharge" refers to a volume of water that exits the dripper per unit time.

In some embodiments irrigation pipe <NUM> is inclined at a gradually varying slope, and in some embodiments irrigation pipe <NUM> is inclined at a slope that varies non-continuously.

<FIG> is a schematic illustration of irrigation system <NUM>, in embodiments in which a varying slope is employed. Irrigation system <NUM> can comprise water supply system <NUM>, one or more inclined irrigation pipe <NUM> and a plurality of drippers <NUM> (not shown, see, e.g., <FIG> and <FIG>). In the representative illustration of <FIG>, the irrigation system <NUM> comprises a distribution conduit <NUM> into which water is discharged from system <NUM>. Conduit <NUM> is provided with holes <NUM> to which irrigation pipes <NUM> are connected with suitable connectors (not shown). The irrigation pipes <NUM> are optionally and preferably placed between furrows <NUM> that are typically used for flooding and are arranged in a slope <NUM> for compensating in losses in flow along the irrigation pipes <NUM>. Slope <NUM> can vary (gradually or non-continuously) along the irrigation pipes <NUM>.

For example, irrigation pipe <NUM> may be inclined at a gradually varying slope with a higher slope (in absolute value) at the beginning of the irrigation pipe <NUM> and a lower slope (in absolute value) at one or more location downstream pipe <NUM>. It was found by the Inventors that this can increase the water flow rate, and can maintain a generally uniform pressure in all drippers <NUM>. In some embodiments irrigation pipe <NUM> is inclined at a gradually varying slope that is selected such that a water discharge along a length of pipe <NUM> varies by no more than about <NUM>%, or no more than <NUM>%, or no more than <NUM>%, or no more than <NUM>%, or no more than <NUM>%, or no more than <NUM>%, or no more than <NUM>%.

The varying slope is optionally and preferably selected such that for at least one pair of drippers in pipe <NUM>, more preferably for at least two pairs of drippers in pipe <NUM>, more preferably for at least three pairs of drippers in pipe <NUM>, more preferably for any pair of drippers in pipe <NUM>, the ratio between the slope S<NUM> at a location of one of drippers of the pair and the slope S<NUM> at a location of another one of the drippers of the pair, is equal or approximately equal to the nth power of the ratio between the distances of the drippers from the lowermost point of pipe <NUM> (e.g., the farthest point of pipe <NUM> from conduit <NUM>). Mathematically, this can be expressed as S<NUM>/S<NUM>∝[(L-ℓ<NUM>)/(L-ℓ<NUM>)]n, where L is the length of pipe <NUM>, ℓ<NUM> is the distance between the highest point along pipe <NUM> and one of drippers of the pair, and ℓ<NUM> is the distance between the highest point along pipe <NUM> and the other dripper of the pair. The value of the exponent n is preferably from about <NUM> to about <NUM>, e.g., about <NUM> or about <NUM>.

Reference is made to <FIG> which are schematic illustrations of a dripper <NUM>, according to some embodiments of the present invention. Dripper <NUM> optionally and preferably comprises a plurality of holes functioning as water inlets <NUM>. However, this need necessarily be the case, since, for some applications, the end of the dripper can serves as an inlet. Dripper <NUM> can be useful in irrigation systems such as, but not limited to, the irrigation systems illustrated above with reference to <FIG>, <FIG> and <FIG>. Dripper <NUM> can be attached to, or located in, one or more irrigation pipes <NUM>. Dripper <NUM> can be integrated into irrigation pipes <NUM> during pipe manufacturing process.

In the representative illustration of <FIG>, dripper <NUM> is assembled from an external hollow element <NUM>, e.g., in a shape of a hollow tube; and having one or more water inlets <NUM> for intaking water into dripper <NUM>, and one or more water outlets <NUM> for discharging water from the dripper <NUM>. Dripper <NUM> also comprises an internal element <NUM> having a diameter that is smaller than the diameter of the external hollow element <NUM>, such that when the internal element <NUM> is inserted inside external hollow element <NUM>, a water pathway <NUM> is formed in a space therebetween. Pathway <NUM> can extend from one end <NUM> of dripper <NUM> to another end <NUM> of dripper <NUM>. End <NUM> is optionally and preferably closed. According to the invention water pathway <NUM> is formed such that there is at least one inlet-outlet pair that is connected by a straight line that is within water pathway <NUM>. This allows at least a portion of the water to flow along a straight line from one or more of the inlet(s) <NUM> to one or more of the outlet(s) outlet <NUM>, and is unlike drippers having, for example, zigzag or labyrinth pathways.

Herein "an inlet-outlet pair" is a pair that includes one of inlet(s) <NUM> and one of outlet(s) <NUM>.

Water inlets <NUM> can be in the form of a plurality of small cavities having a diameter from about <NUM> to about <NUM> and inter-inlet intervals of from about <NUM> to about <NUM>. Water outlets <NUM> are preferably configured to discharge water from the dripper to provide a desired discharge flow rate of water out from the dripper to the soil or ground. The hole diameter of the water outlets <NUM> is typically from about <NUM> to about <NUM>. Water outlets <NUM> of dripper <NUM> can optionally and preferably be in communication with a hole <NUM> (shown in <FIG>) located in the inclined irrigation pipe <NUM> (shown in <FIG>).

According to some embodiments of the invention dripper <NUM> is characterized by a pressure-discharge dependence which comprises a linear relation between a discharge rate Q (water volume per unit time) at outlet <NUM> and an inlet pressure P at inlet <NUM>. This relation can be expressed mathematically as Q=a<NUM>P+a<NUM>, where a<NUM> is an inlet pressure coefficient and a<NUM> is an offset parameter. A typical value for a<NUM> is from about <NUM> cubic centimeters per hour per cm H<NUM>O to about <NUM> cubic centimeters per hour per cm H<NUM>O or from about <NUM> cubic centimeters per hour per cm H<NUM>O to about <NUM> cubic centimeters per hour per cm H<NUM>O or from about <NUM> cubic centimeters per hour per cm H<NUM>O to about <NUM> cubic centimeters per hour per cm H<NUM>O. A typical value for a<NUM> is from about <NUM> to about <NUM> cubic centimeters per hour, or from about <NUM> cubic centimeters per hour to about <NUM> centimeters per hour, or from about <NUM> cubic centimeters per hour to about <NUM> cubic centimeters per hour.

<FIG> illustrates a longitudinal cross-sectional illustration of dripper <NUM>, according to some embodiments of the present invention, and <FIG> illustrates an exploded side view of external hollow element <NUM> (right side) and internal element <NUM> (left side), according to some embodiments of the present invention.

The dripper <NUM> may comprise an external hollow element <NUM> having a first end <NUM>, which may be closed. Internal element <NUM>, with a head <NUM>, may be inserted into the external hollow element <NUM>. Head <NUM> of internal element <NUM> preferably closes one end <NUM> of external hollow element <NUM> after these elements are assembled together. External hollow element <NUM> can have a plurality of water inlets <NUM> at one end <NUM> and one or more water outlets <NUM> at the other end <NUM>.

With reference to <FIG>, an internal diameter dint is typically defined between the two farthest antipodal points on an outer wall <NUM> of internal element <NUM>. An external diameter dext is typically defined between the two farthest antipodal points on an inner wall <NUM> of external hollow element <NUM>. When the internal element <NUM> is introduced into the external hollow element <NUM>, a water pathway <NUM> is created having a width W. The width W is optionally and preferably be set to provide a sufficiently narrow water pathway <NUM> and to provide a small hydraulic diameter (DH) for reducing flow within the dripper <NUM>.

The hydraulic diameter (DH) is a parameter that is defined as four times the ratio between a flow area A and a wetted perimeter of a conduit, P, as defined in Equation I: <MAT>.

I A can be the cross-sectional area of the water pathway <NUM> in dripper <NUM> and P can be the wetted perimeter of the cross-section, in which case DH is referred to as the hydraulic diameter of pathway <NUM>.

For example, when water pathway <NUM> has a circular shape, the hydraulic diameter according to EQ. I above is reduced to the diameter of the circle forming the pathway.

A typical hydraulic diameter of pathway <NUM>, suitable for the present embodiments is from about <NUM> to about <NUM>. Other values for hydraulic diameter are also contemplated, provided that clogging within the water pathway <NUM> is reduced or inhibited, as further discussed hereinbelow with reference to <FIG>.

When water pathway <NUM> has an annulus shape, the hydraulic diameter is defined as the width W of the pathway, which can be calculated as the difference between the internal diameter d<NUM> of external hollow element <NUM>, and the external diameter d<NUM> of internal element <NUM>, according to EQ.

It is appreciated that the water flow rate decreases in a channel as its hydraulic diameter decreases.

The Inventors of the present invention found that by utilizing a narrow hydraulic diameter dripper according to preferred embodiments of the present invention, particular at a low operating pressure, may provide a low discharge flow rate when exiting from dripper <NUM>. Small hydraulic diameter may be achieved by providing a sufficiently large relative surface area of the narrow water pathway <NUM>, and/or by reducing the energy of water flowing in the water pathway <NUM>, for example, by increasing friction for water flow of the narrow water pathway <NUM> of the dripper <NUM>. An enlarged relative surface area of water pathway <NUM> can be achieved, for example, by making shaped pathway. For example, the pathway can be shaped as a polygon (e.g., a triangle, a square, etc). An enlarged relative surface area of water pathway <NUM> can alternatively or additionally be achieved by providing a sufficiently long pathway between the inlet <NUM> and outlet <NUM>.

Particle accumulation at the dripper entrance can cause clogging and reduced flow discharge, thus resulting in flow discharge decrease or no flow.

The advantage of having a pathway as described above can be better understood with reference to <FIG> which illustrates a perspective side view of dripper <NUM> according to some embodiments of the present invention. Shown is an obstacle <NUM>, such as a particle or an air bubble, in its water pathway <NUM>, which, in the illustrated embodiment, has an annulus shape. Obstacle <NUM> can be in contact with inner wall <NUM> of external hollow element <NUM> and outer wall <NUM> of internal element <NUM> of dripper <NUM>, thereby partially or even completely clogging a region pathway <NUM>. However, since pathway <NUM> is not one-dimensional, there are other alternative paths within pathway <NUM> allowing bypass routes <NUM>, <NUM> and <NUM> around any obstacle that may be inside dripper <NUM>. Moreover, the amount of particles entering the dripper may be reduced by providing dripper <NUM> with a narrow entrance. Water inlets <NUM> may be of a size of from about <NUM> to about <NUM>. Thus, pathway <NUM> is not completely blocked by obstacle <NUM>.

In some embodiments there are multiple capillary water inlets <NUM>. Typically, but not necessarily, for example, between <NUM> and <NUM> capillary water inlets are employed. The advantage of having a multiplicity of capillary water inlets is that the capillary water inlets can serve as a filter for dripper <NUM>. and reduce the risk of dripper clogging.

According to some embodiments of the present invention, the hydraulic diameter DH is from about <NUM> to about <NUM>. According to some embodiments of the present invention the external hollow element <NUM> has an inner diameter of from about <NUM> to about <NUM>.

Cross-sectional area of the dripper suitable for the present embodiments can be from about <NUM><NUM> to about <NUM><NUM>, depending on the width of water pathway <NUM>. The water flow rate of water flowing through dripper <NUM>, is typically from about <NUM>/h to about <NUM>,<NUM>/h at a hydraulic pressure of from about <NUM> H<NUM>O to about <NUM> H<NUM>O. For example, a dripper of about <NUM> in length and an annulus about <NUM> in width can produce a flow rate of about <NUM>/h at a pressure of <NUM> H<NUM>O.

The outer surfaces of external <NUM> and internal <NUM> elements may be parallel to each other up to a tolerance of about <NUM>%. The distance between water inlets <NUM> can be from about <NUM> to about <NUM> The distance between water inlets <NUM> and water outlets <NUM> can be from about <NUM> to about <NUM>.

As may further be appreciated, irrigation system <NUM>, by employing the drippers of the present embodiments, and operating them at a low pressure may eliminate a need for pump <NUM> of the kind displayed in <FIG>, and as a result, irrigation pipes <NUM> of the present embodiments may be made of fewer and cheaper raw materials.

In addition, the Inventors found the dripper of the present embodiments allows particles to be washed out by water flowing inside. Even if particles are partially clogged within the dripper of the present embodiments, the partial clogging may unclog when clean water is provided to the dripper, by washing the particle away. As a result, the dripper of the present embodiments has natural, built-in, self-cleaning capabilities.

With reference now to FIGs. 7A and 7B, the plurality of drippers <NUM> in any one of the embodiments of the irrigation system described above can be positioned either horizontally or vertically relative to the position of the irrigation pipe <NUM>, as illustrated in FIG. 7A and FIG. 7B, respectively.

<FIG> are cross-sectional illustrations of partial water pathway inside a dripper <NUM>, according to some embodiments of the present invention.

As described hereinabove in <FIG>, water pathway <NUM> is created by assembling the internal element <NUM> with the external hollow element <NUM>. Internal element <NUM> may have alternative cross-sections such by utilizing the water pathway <NUM> in a shape of a partial ring, namely, by partially utilizing at least a portion of the annulus <NUM>. Any of the components of dripper <NUM> may comprise molded plastic. Internal element <NUM> may be inserted into external hollow element <NUM>.

In some embodiments of the present invention one or more covers may be put on one or more sides of external hollow element <NUM>, thereby closing one or more of its ends.

<FIG> are schematic illustrations showing cross-sectional views of dripper <NUM>, according to several embodiments. <FIG> illustrate a side view (<FIG>) and a sectional view along the A---A line (<FIG>) of dripper <NUM> in embodiments in which dripper <NUM> comprises diagonal holes in the sides and exit holes under a dressed head (the left side is not shown in the drawing). <FIG> illustrate a side view (<FIG>) and a sectional view along the B-B line (<FIG>) of dripper <NUM> in embodiments in which dripper <NUM> comprises elliptically shaped water inlet (see also <FIG>, below) with a filter <NUM>. <FIG> illustrate a side view (<FIG>) and a sectional view along the C---C line (<FIG>) of dripper <NUM> in embodiments in which dripper <NUM> comprises an elliptically shaped water inlet without a filter (see also <FIG>, below). <FIG> illustrate a side view (<FIG>) and a sectional view along the D---D line (<FIG>) of dripper <NUM> in embodiments which are similar to those shown in <FIG>, except for a shorter distance between the dripper's end and the exit holes. <FIG> illustrate a side view (<FIG>) and a sectional view along the E-E line (<FIG>) of dripper <NUM> in embodiments in which are similar to those shown in <FIG>. except that dripper <NUM> comprises diagonal holes under a cover. <FIG> illustrate a side view (<FIG>) and a sectional view along the F---F line (<FIG>) of dripper <NUM> in embodiments in which are similar to those shown in <FIG>, except that the outer shape is tapered to reduce friction.

Perspective illustrations of the drippers illustrated in <FIG> are shown in <FIG>, where <FIG> corresponds to <FIG>, <FIG> corresponds to <FIG>, <FIG> corresponds to <FIG>, <FIG> corresponds to <FIG>, <FIG> corresponds to <FIG>, and <FIG> corresponds to <FIG>. The cover on external hollow element <NUM> is shown in <FIG> at <NUM>.

The length of external hollow element <NUM> and internal element <NUM> may be between about <NUM> and <NUM>. The diameter of external hollow element <NUM> may be between about <NUM> and <NUM>, and the diameter of internal element <NUM> may be between about <NUM> and <NUM>. The size of inlet <NUM> and outlet <NUM> may be between about <NUM> and <NUM>. The height of "baths" <NUM> may be between about <NUM> and <NUM> micron larger than narrow space <NUM> and the width of narrow space <NUM> may be between about <NUM> and <NUM> micron.

It will be appreciated that although the drippers and their components that were described herein have a cylindrical shape, they may also be manufactured in other shapes such that the external hollow element and the internal element described herein may be in any shape or form, such as, ellipse, square, rectangular, triangular, hexagonal, octagonal, etc..

Alternatively or additionally, the dripper according to the present embodiments may have an elliptically shaped water inlet, or a plurality of such shaped inlets.

Alternatively or additionally, the dripper according to the present embodiments may have a water inlet having any geometric shape, such as square, rectangle, triangle and circle.

With reference to <FIG>, there is illustrated a perspective side view of an assembled dripper <NUM> having an elliptically shaped water inlet <NUM> according to some embodiments of the present embodiments. As shown, the water inlet is positioned perpendicular to the drip.

Reference is now made to <FIG>, which displays a perspective side view of an assembled dripper <NUM> having an elliptically shaped water inlet <NUM> and comprising a filter according to some embodiments of the present embodiments. The elliptical water inlet <NUM> (or a plurality of such inlets) comprises a filter <NUM> in various possible shapes (grid, cross-sectional or longitudinal grooves). As shown, the water inlets <NUM> are positioned perpendicular to the drip <NUM>.

In addition to the vertical elliptical inlet <NUM> as displayed in <FIG>, there are additional inlets, which are not vertical to the drip <NUM>, through which water enters when their flow direction is generally at an obtuse angle θ to the flow of water in the drip. Typical values of θ include, without limitation, from about <NUM>° to about <NUM>°, or from about <NUM>° to about <NUM>°, or from about <NUM>° to about <NUM>°, e.g., about <NUM>°. <FIG> illustrate a cross sectional view (<FIG>) and a perspective side view (<FIG>) of an assembled dripper having an elliptically shaped water inlet <NUM> and an additional water inlet <NUM> oriented diagonally with respect to a normal to an outer surface of an external hollow element <NUM> according to some embodiments of the present embodiments.

The inlets reach a level where water enters the drip and creates turbulence that prevents particles from accumulating in the water entry area. The drip water entry area is the area where particles may accumulate and may cause a partial or complete blockage of the drip, such that if particles have been introduced into the drip <NUM>, then the particles may not accumulate and may exit through the outlet as a result of the dripper's three-dimensional shape and smoothness. The water inlets <NUM> may be oriented in a diagonal position with respect to a normal to an outer surface of the external hollow element <NUM>, which may produce turbulent flow of water in entry to the dripper inlet.

<FIG> are schematic illustrations showing a perspective view (<FIG>) and a cross sectional view (<FIG>) of the assembled dripper in embodiments of the invention in which the internal element is held only from one side.

As described herein above, it was realized by the inventors of the present invention that drip irrigation systems work at pressures between <NUM> to <NUM> bar and cannot be applied in large commercial fields using a work pressure lower than <NUM> bar. The inventors devised an irrigation system having an irrigation pipe inclined at a slope that can be selected such that a water discharge along a length of the pipe varies by no more than <NUM>%, or no more than <NUM>%, or no more than <NUM>%, or no more than <NUM>%, or no more than <NUM>%, or no more than <NUM>%, or no more than <NUM>%.

<FIG> is a graph plotting a difference in percentage between a dripper with high discharge to a dripper with low discharge as a function of a field slope for inlet heads about <NUM>, <NUM>, <NUM>, <NUM> and <NUM>, with <NUM> drippers per meter, pipe length of about <NUM> and diameter of about <NUM>, as obtained in experiments performed according to some embodiments of the present invention and listed in Table <NUM>.

Pressure at the last dripper was set to an estimated value and the dripper discharge was calculated. The head loss to the next dripper was calculated and the head change due to the slope to determine the pressure at the inlet of that dripper. The discharge of the two drippers was summed and so forth to the beginning of the pipe. Microsoft Excel "goal seek" function was used to change the pressure at the last dripper to set the target inlet head according to Table I above. The field slope was varied to evaluate slopes for efficiently operating the irrigation system of the present invention given maximum discharge difference of <NUM>%.

The pipe slope can cause higher pressure at the end (depending on the slope), and thus, higher dripper discharge. The increased discharge towards the pipe end can cause lower discharge variability along the pipe and acceptable uniformity in yields.

All pipes can be connected at the end by a "collector" tube which can be connected to a valve at its end (not shown here). The valve can be opened periodically to clean the system during irrigation (no less than once every <NUM> weeks) for duration of <NUM>-<NUM> minutes. Opening the valve can create faster flow rate inside the pipes which can clean the drippers from accumulated dirt. This procedure can work especially well in low pressure systems (up to <NUM>) where flow rates are typically slow. This valve can be controlled either manually or with a timer or using any irrigation control method. The flow rate in the pipe during the flushing depends on the pipe length (L), diameter (D) and smoothness (C), inlet head (Hf) and slope of the field and can be calculated using Hazen-Williams equation as provided below in EQ. III: <MAT>.

<FIG> is a graph showing a relative discharge of <NUM> different drippers before and after flushing, as obtained in experiments performed according to some embodiments.

<FIG> is a graph showing water discharge in a pipe conduit during flushing as a function of a slope and an inlet pressure, for a pipe conduit having a length of about <NUM> and a diameter of about <NUM>, as obtained in experiments performed according to some embodiments.

As can be seen in <FIG>, flushing of the pipe increased the discharge of clogged drippers to the original values.

Pipe flushing can create higher discharge and can waste water. However, pipe flushing for a short duration at the end/beginning of irrigation can keep the wasted amount of water minimal while keeping the drippers unclogged. The discharge of water through the pipe is shown in <FIG>, which exemplifies that pipe flushing with inlet head of about <NUM> and a slope of about <NUM>% for duration of <NUM> minutes can waste <NUM> liters of water, which is a very small amount relative to surface irrigation.

The irrigation system according to the present invention can be designed to connect to existing agricultural water supply systems, which can be used for flood irrigation.

Field slope can be used as a design variable to directly influence the pipe pressure, and thus, the drippers' flow discharge along its length. The slope along the pipe can vary depending on the pipe length, the density of the drippers (number per tube length), and the water head at the inlet. As water flows in the pipe, there can be a pressure drop along the flow pathway due to friction, and therefore, there can be variations in drip flow.

<FIG> are graphs of the inlet pressure as a function of the conduit length for a slope of <NUM>° (<FIG>), varying slope (<FIG>), and slope selected to ensure a uniform flow rate (<FIG>), as obtained in experiments performed according to some embodiments.

As shown in <FIG>, in a <NUM> pipe without a slope (slope of <NUM>°), the pressure decreased from <NUM> at the beginning of the pipe to <NUM> at its end. This pressure difference exhibits a difference of <NUM>% in the flow rates. Head loss in the flow along the dripper can be calculated by the Darcy-Weisbach equation as described above.

Fields that are typically irrigated by flooding can have small slopes of between about <NUM>% and about <NUM>%. Therefore, in conventional dripping systems, where the working pressures are high of about <NUM>-<NUM>, the slope has no significant effect, as the height differences are negligible relative to working pressures.

According to an embodiment, the system in which the working pressure can be close to zero, small height differences along the pipe length can have a substantial effect on the pipe pressure and the drippers flow rate. The slope <NUM>, S(<NUM>), can vary along the pipe to compensate for the pressure loss.

The slope at any point l along pipe <NUM> can be expressed mathematically as a slope function S(l). The slope function can be input to a controller of a shoveling tool, such as, but not limited to, a laser guided land-leveling system, to form a varying slope in a soil, and inclined irrigation pipe <NUM> with drippers <NUM> can be deploying, generally along the varying slope.

A representative slope function suitable for the present embodiments is: <MAT> where K is a dimensionless constant. Typically, K is from about <NUM> to about <NUM> or from about <NUM> to about <NUM>, where L is the length of the irrigation pipe <NUM>, fd is a friction factor, q is a flow rate in irrigation pipe <NUM> per unit length, g is the gravitational acceleration, DH is a hydraulic diameter of said irrigation pipe <NUM>, and l is a distance along irrigation pipe <NUM> from the highest level thereof.

Another representative slope function suitable for the present embodiments is: <MAT> where c is a smoothness coefficient of the pipe's material, and G, α, β, γ and δ and ε are constant parameters. A typical value for G is from about <NUM> to about <NUM>, a typical value for any of α, β and γ is from about <NUM> to about <NUM>, and a typical value for δ is from about <NUM> to about <NUM>. In some embodiments of the present invention at least two, more preferably all, of α, β and γ have the same value.

Since the pressure loss is greater at the beginning of the pipe and gradually decreases along the pipe, there can be a steeper slope at the beginning of the pipe and can be more moderate along the pipe length. In some embodiments of the present invention the slope S is selected also based on the distance between drippers <NUM>. The flow rate can also be affected by the distance between drippers, since each dripper can reduce the volume of water flowing through the pipe.

At the beginning of the pipe, the water flows at a maximum flow rate, and when water reaches the first dripper after a distance x, the flow rate gradually decreases in accordance with the flow rate in the dripper and so on. In the last portion of the pipe (up to the last dripper) the flow rate in the pipe equals the flow rate in the last dripper.

In <FIG>, the slope can be determined so that the drip flow along the pipe is generally uniform. <FIG> shows that uniform flow can be achieved by the slope shown in <FIG>.

As used herein the term "about" or "approximately" refers to ±<NUM>%.

Claim 1:
A water irrigation dripper (<NUM>), comprising:
an external hollow element (<NUM>) having at least one water inlet (<NUM>) and at least one water outlet (<NUM>); and
an internal element (<NUM>) inside said external hollow element (<NUM>) to form in a space between said elements (<NUM>, <NUM>) a water pathway (<NUM>) that at least partially surrounds said internal element (<NUM>), said water pathway (<NUM>) being other than a one-dimensional pathway allowing at least a portion of water entering said water pathway (<NUM>) to flow within the water pathway (<NUM>) along a straight line from one or more of said inlets (<NUM>) to one or more of said outlets (<NUM>), wherein when a particle (<NUM>) in said water clogs a region in said water pathway (<NUM>) by contacting both an inner wall (<NUM>) of said external hollow element (<NUM>)and an outer wall (<NUM>) of said internal element (<NUM><NUM>), said water flows around said particle (<NUM>) in said water pathway (<NUM>) along a plurality of alternative bypass flow routes (<NUM>, <NUM>, <NUM>).