Channel-less drip irrigation emitter

Abstract

Channel-less flow devices for irrigation, having improved operating parameters are disclosed. The emitters can include a body that defines a circular pocket diaphragm pocket configured to receive a correspondingly-sized diaphragm therein, a lands, and / or a labyrinth passage recessed within the body to regulate flow. The emitter can be designed for low activation pressure and consistent pressure compensation operation without having a channel formed therein. To achieve pressure-compensation, parameters such as depth of the lands and a position of an outlet relative to the diaphragm can be modulated to achieve constant flow parameters.

Description

Atty. Dkt. No.: MIT 25861 PCT | 88212-425440 CHANNEL-LESS DRIP IRRIGATION EMITTER CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present disclosure claims priority to and the benefit of U.S. Provisional Application No.63 / 652,023, entitled “Channel-Less Drip Irrigation Emitter,” filed on May 26, 2024, the content of which is incorporated by reference herein in its entirety. FIELD

[0002] The present disclosure relates to flow devices for irrigation, and more particularly relates to a low-pressure, compact, channel-less pressure-compensating emitter designed to enable affordable, clean-energy technology for drip irrigation. BACKGROUND

[0003] Due to climate change and population growth, there is a push for sustainable agricultural intensification to meet increasing global food demand without depleting resources. This push is especially evident in lower, middle-income countries where population growth and water scarcity are large concerns. With affordable, sustainable irrigation solutions, small farmers of lower, middle-income countries can increase their production, thereby enhancing household food security without decreasing water availability.

[0004] Drip irrigation is one method of sustainable irrigation that has shown to be very effective at saving water. Drip irrigation is a form of irrigation that can deliver water directly to the root zone via a network of pressurized tubing and emitters, avoiding water losses associated with conveyance and evaporation. Emitters can be flow metering devices that ensure targeted and regulated watering of crops. In some embodiments, these emitters can be positioned in-line within the tubes that flow fluid to crops by thermally bonding the emitters to the inner wall of the drip line during tube extrusion / pultrusion. The in-line emitters can be molded and inserted into the tube at set spacings and are used for growing horticultural crops. When compared to conventional irrigation methods, such as flood or furrow irrigation, drip irrigation has been about 26-65% more water efficient while attaining similar or higher crop yields.Atty. Dkt. No.: MIT 25861 PCT | 88212-425440

[0005] Adoption of drip irrigation solutions has been slow worldwide for a variety of a reasons. First, drip irrigation uses substantial capital and operating expenses due to its need to be pressurized, which poses a financial burden for small farmers. To improve the affordability of drip irrigation, low-pressure drip irrigation attempts to reduce the operating energy requirement. For example, inline emitters that are bonded to the inside of irrigation tubing during manufacturing have been researched with the aim of increasing adoption. These low-pressure drip emitters can reduce the hydraulic power needed to operate the drip system by decreasing the activation pressure. This change lowers operating expenses by requiring less energy to run, while making photovoltaic (PV) panel integration much more affordable at least because low pressure emitters need smaller pumps than conventional emitters. However, conventional low pressure emitters have channels that are prone to clogging, which severely limits their usability. Clogging refers to the obstruction or blockage of the flow passage within the emitter, often caused by silt, bacteria, microbial particles sediment, organic matter, or mineral deposits, which reduces or halts the emission of water that cannot be filtered out by conventional means without intensive capital costs or significant human labor. Clogging of emitters can lead to over-irrigation and continual maintenance costs for system replacement, which limits long-term performance and overall adoption of drip systems.

[0006] Accordingly, there is a need for an improved flow device for use in an irrigation system that exhibits strong clog resistance performance. SUMMARY

[0007] The present application is directed to low-pressure, compact, channel-less emitters capable of working in drip irrigation systems that operate in a pressure-compensating (PC) regime. The emitter can include a body having a circular diaphragm pocket, a correspondingly-shaped diaphragm, a lands, and a labyrinth forming a tortuous passage through the body. A top cover can be placed on top of the body to seal the diaphragm within the diaphragm pocket. The lands can be devoid of a channel and / or weir to prevent and / or minimize clogging of the emitter. The diaphragm pocket can include a cavity having an inlet and an outlet formed therein to flow fluid proximal to the diaphragm and to deflect the diaphragm towards the lands. Once deflected, the fluid can flow above the diaphragm and out of the outlet which is offset from a center of the diaphragm.Atty. Dkt. No.: MIT 25861 PCT | 88212-425440

[0008] One exemplary embodiment of an irrigation emitter includes a body having a volume defined between a pair of opposed walls, a pair of opposed sidewalls, and a top wall having a proximal-facing surface that is opposed to a bottom wall having a distal-facing surface. The body includes a diaphragm pocket recessed into the proximal-facing surface, a diaphragm, a lands, and a labyrinth. The diaphragm is disposed on a diaphragm seat such that a gap is formed between the diaphragm and the lands in a resting configuration. The diaphragm is configured to transition from the resting configuration to a curved configuration with application of increased pressure to minimize a size of the gap. The lands is disposed within the diaphragm pocket, with the lands having a first opening that defines an inlet and a second opening that defines an outlet that is offset from a center of the diaphragm. The lands is devoid of a channel. The labyrinth is in fluid communication with the diaphragm pocket, with the labyrinth forming a tortuous path within the proximal-facing surface.

[0009] The emitter can have an activation pressure as low as 0.3 bar. An offset of the outlet from the center of the diaphragm is approximately in a range of about 0.4 millimeters to about 2.5 millimeters. In some embodiments, the outlet can include a chamfered edge. The body can receive the fluid from an irrigation system.

[0010] The diaphragm can at least partially overlap with the outlet in the curved configuration. In some embodiments, the diaphragm can completely cover the outlet in the curved configuration. The diaphragm pocket can be circular. A shape of the diaphragm can correspond to a shape of the diaphragm pocket. A depth of the lands can be approximately in a range of about 0.4 millimeters to about 0.8 millimeters. In some embodiments, a transfer channel can connect the labyrinth with the inlet of the lands. In some embodiments, the emitter can include a shelf formed within the diaphragm pocket on which the diaphragm is disposed.

[0011] One exemplary embodiment of a method of controlling flow during irrigation includes flowing a fluid into a body of an emitter, with the body having a volume that is defined between a pair of opposed walls, a pair of opposed sidewalls, and a top wall having a proximal-facing surface that is opposed to a bottom wall having a distal-facing surface. The fluid that flows passes onto a diaphragm disposed in a diaphragm pocket recessed into the proximal-facing surface, with the diaphragm pocket having a first opening that defines an inlet and a second opening that defines an outlet. The fluid enters a labyrinth that is in fluid communication with the diaphragm pocket to flow through a plurality of recessed channelsAtty. Dkt. No.: MIT 25861 PCT | 88212-425440 within the proximal-facing surface, exits the labyrinth into a portion of the diaphragm pocket disposed below the diaphragm, flows proximal to the diaphragm to deflect the diaphragm onto a lands disposed in the diaphragm pocket that extends proximally from the distal-facing surface, and flows through the outlet out of the body.

[0012] The method can further include adjusting a flow rate of the emitter without changing activation pressure by changing a depth of the lands or a position of the outlet. A constant flow rate can be set by increasing a hydraulic resistance of the emitter linearly with pressure above the activation pressure. Increasing the hydraulic resistance can further include offsetting a position of the outlet from a center of the diaphragm. The offset of the outlet from the center of the diaphragm can be approximately in a range of about 0.4 millimeters to about 2.5 millimeters.

[0013] In some embodiments, the diaphragm can be deflected to at least partially overlap with the outlet. At least a portion of a circumference of the diaphragm can occlude at least a portion of the area of the outlet. The diaphragm pocket can be devoid of a channel.

[0014] In some embodiments, the method can include positioning the body within one or more tubes of an irrigation system such that it is in-line with a flow of fluid that passes through the one or more tubes. The fluid can deflect the diaphragm into a curved configuration when the diaphragm contacts the lands to allow fluid to pass between the diaphragm and the lands to the outlet.

[0015] One exemplary embodiment of a hydraulic system can include a pump configured to produce water using hydraulic pressure, a drip emitter as discussed above, and a tube for connecting the pump to a multiplicity of drip emitters. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] This disclosure will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0017] FIG.1 is an exploded perspective view of one example of an emitter of the present embodiments;

[0018] FIG.2A is a perspective view of the emitter of FIG.1 illustrating an example embodiment of operation of the emitter;Atty. Dkt. No.: MIT 25861 PCT | 88212-425440

[0019] FIG.2B is a perspective view of the emitter of FIG.2A illustrating an example embodiment of operation of the emitter;

[0020] FIG.3A is a top view of the emitter of the present embodiments;

[0021] FIG.3B is a side cross-sectional view of the emitter of FIG.3A viewed along the line A-A prior to a diaphragm contacting a lands of a diaphragm pocket of the emitter;

[0022] FIG.3C is a side cross-sectional view of the emitter of FIG.3A viewed along the line A-A after the diaphragm contacts the lands of the diaphragm pocket of the emitter;

[0023] FIG.4A is a schematic top view of a diaphragm covering an outlet of an emitter of the present embodiments;

[0024] FIG.4B is a perspective top view of the diaphragm partially covering the outlet of the emitter of FIG.1;

[0025] FIG.4C is a magnified perspective view of the emitter of FIG.1, with the outlet having a chamfered edge;

[0026] FIG.5A is a graph illustrating pressure curves as a function of flow rate and pressure of an emitter having various outlet positions and a lands depth, hlands, of 0.4 millimeters;

[0027] FIG.5B is a graph illustrating pressure curves as a function of flow rate and pressure of an emitter having various outlet positions and a lands depth, hlands, of 0.6 millimeters;

[0028] FIG.5C is a graph illustrating pressure curves as a function of flow rate and pressure of an emitter having various outlet positions and a lands depth, hlands, of 0.8 millimeters;

[0029] FIG.6 is a chart illustrating activation pressures at the outlet positions and lands depths of FIGS.5A-5C; and

[0030] FIG.7 is a table summarizing the results of FIGS.5A-5C with outlet coverage and slope of pressure curves of FIGS.5A-5C.Atty. Dkt. No.: MIT 25861 PCT | 88212-425440 DETAILED DESCRIPTION

[0031] Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the devices and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the systems and methods specifically described herein and illustrated in the accompanying drawings are non- limiting exemplary embodiments and that the scope of the present disclosure is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present disclosure. Terms commonly known to those skilled in the art for components and / or processes of the structure, function, manufacture, and use of the devices and methods disclosed herein and the like may be used interchangeably herein. A person skilled in the art, in view of the claims, present disclosure, and knowledge of the skilled person, will understand such terms are merely examples of such components and / or processes, and other components, designs, processes, and / or actions are possible.

[0032] The present disclosure generally relates to flow devices for use in conjunction with drip irrigation systems. The types of drip emitters currently out on the market can include pressure-compensating (PC) drip emitters and non-pressure-compensating (NPC) drip emitters. PC drip emitters are passive flow control devices that have a constant outlet flow rate above a minimum inlet pressure called the activation pressure. In drip irrigation systems deployed on medium-large fields (>1 hectare) or on undulating terrains, this characteristic can ensure uniform irrigation across the field at least because pressure variation in the drip lines can lead to significant irrigation variation to plants. PC inline drip emitters can be injection molded in 2 components (an emitter body and a top cover) which are typically welded together and then thermally bonded to the inner wall of the drip line during tube extrusion / pultrusion itself. To produce PC action, a rubber diaphragm is placed between the top cover and emitter body; its interaction and deformation with flow helps create the PC action. Commercially offered PC emitters have activation pressures of greater than or equal to about 0.4 bar, are about 0.3 inches to about 0.45 inches wide, and about 1.5 inches to about 2 inches long. PC emitters can offer uniform water application to all crops in a field regardless of the terrain or length of tubing and have a constant flow rate as long as the inletAtty. Dkt. No.: MIT 25861 PCT | 88212-425440 pressure is above an ‘activation’ pressure. Low-pressure drip emitters can reduce the hydraulic power needed to operate the drip system by decreasing the activation pressure.

[0033] Conventional PC emitters include a labyrinth (also called the tortuous path), a flexible diaphragm, and a channel formed therein. The channel is the smallest feature that can often be prone to clogging. Emitters of the present embodiments, in addition to being low- pressure, can be clog-resistant to remedy the clogging seen in conventional emitters by removing the channel. These channel-less emitters of the present embodiments can still reach activation at low-pressures, thereby maintaining the reliability, longevity, and affordability expected of drip systems, while significantly improving clog resistance. A person having ordinary skill in the art will recognize that removing the channel presents a challenge in conventional emitters as the channel is responsible for maintaining low pressure and PC capabilities of the emitter. In conventional emitters with a channel, it is known that activation occurs when the diaphragm completely covers the outlet, but activation in a channel-less emitter is not known.

[0034] At least one novel feature of the present embodiments includes a channel-less emitter with a circular diaphragm that is capable of creating pressure-compensation by adjusting one or more of an outlet position or a lands depth thereof. That is, the emitter of the present embodiments can include the ability to define when activation will occur under specific operating conditions, such as desired flow rate and activation pressure, while maintaining pressure-compensating behavior in a channel-less emitter. The emitters of the present embodiments can replace the pressure-varying hydraulic resistance of the channel with hydraulic resistance stemming from offsetting the outlet of the emitter away from the center axis of the emitter pocket, which is where it is conventionally located. For example, a position of an outlet of the emitter can be moved off-center, and as the flexible diaphragm deflects and begins to cover the offset outlet, the gap that flow is able to exit through decreases, which produces a hydraulic resistance that allows for a constant flow rate that is seen in PC emitters despite the absence of a channel.

[0035] FIG.1 illustrates an example of an emitter 10 of the present embodiments. The emitter 10 of the present embodiments can include at least three novel aspects that distinguishes the emitter 10 from conventional drip irrigation components: i) maintaining a circular diaphragm pocket while eliminating use of a channel or weir and still achieving pressure-compensating behaviors, i.e., constant flow rate; ii) optimizing a location of anAtty. Dkt. No.: MIT 25861 PCT | 88212-425440 outlet to achieve constant flow rate at activation pressure through the emitter 10; and iii) optimizing a size of the emitter 10 to remain compact while supporting adequate pressure drop through the labyrinth. A detailed description of each of these features and / or components is included in greater detail below.

[0036] In some embodiments, one or more emitters 10 can be disposed in a tube (not shown) to ensure targeted and regulated watering of crops. For example, the emitters 10 can be spaced a distance apart within the tube, with the spacing being based, at least in part, on the crop being grown. Conventional manufacturers may offer products with nominal emitter spacings that are one or more of, for example, 12 inches, 16 inches, 18 inches, 24 inches, and / or 36 inches, of which farmers pick a spacing that best serve their crop, crop layout, and / or harvesting plans.

[0037] As shown, the emitter 10 can include a body 12 having a diaphragm pocket or diaphragm cavity 14 configured to receive a diaphragm 16 therein. The body 12 can be made from made from low- or high-density polyethylene and include a volume defined between a pair of opposed walls, a pair of opposed sidewalls, and a top wall having a proximal-facing surface that is opposed to a bottom wall having a distal-facing surface. As shown, the diaphragm pocket 14 and the diaphragm 16 can be circular such that a shape of the diaphragm 16 conforms to a shape of the diaphragm pocket 14. The diaphragm 16 can be made of silicone rubber or any other elastomeric material or membrane that can be disposed within the diaphragm pocket 14. The diaphragm pocket 14 can include a seat or ledge 18 for placement of the diaphragm 16. The diaphragm pocket 14 can define a diaphragm seat 15 at a bottom surface thereof. As inlet pressure above the diaphragm 16 increases, the diaphragm 16 can deflect towards a lands 20 to a degree such that contact may occur therebetween. Increasing pressure may increase interaction or contact between the diaphragm 16 and the lands 20, thereby modulating hydraulic resistance, ensuring that the flow rate is constant (or at least substantially constant, with a person skilled in the art being understand what constitutes a constant or substantially constant flow rate), as discussed in greater detail below.

[0038] The diaphragm pocket 14 can be in fluid communication with a labyrinth 22 that forms a tortuous passage within the body 12 of the emitter 10 to flow fluid through the emitter. The labyrinth 22 can have one U-turn, as shown, though, in some embodiments, two or more U-turns are possible. In some embodiments, the body 12 can include a transfer channel or transfer port 34, as shown in FIG.2B, connecting an exit of the labyrinth 22 andAtty. Dkt. No.: MIT 25861 PCT | 88212-425440 the diaphragm pocket 14, as discussed in greater detail below. In some embodiments, the transfer channel 34 can be disposed on a bottom side (or the like) of the emitter 10 such that a person skilled in the art will recognize how a configuration of the transfer channel 34 can be implemented within the emitter 10 in view of the figures provided and knowledge of the skilled person to transfer water flowing through the labyrinth 22 into the diaphragm pocket 14.

[0039] It will be appreciated that the labyrinth 22 of the present embodiments can have a hydraulic resistance that can support low activation pressure (e.g., which can be defined as 0.4 bar or lower for the purposes of this disclosure), though the activation pressure can go as low as 0.3 bar, and can be compact (fits within an envelope of about 0.37 inches by about 0.3 inches). It will be appreciated that, in some embodiments, low activation pressure can be achieved by increasing the diameter of the diaphragm 16, but this is practically limited by the overall width of the emitter body 12.

[0040] For example, the diaphragm pocket 14 can include an inlet 24 and an outlet 26. In some embodiments, the transfer channel 34 can connect the exit of the labyrinth with the inlet 24 to allow fluid from the labyrinth 22 to enter the diaphragm pocket 14. The outlet 26 can be defined by an opening within the diaphragm pocket 14 that can allow fluid to flow out of the emitter 10, as discussed below. The present design is such that the emitter 10 can be easily configured to run at different flow rates. The depth height, h or hlands, of the lands 20 (also referred to as depth of the lands herein) above the diaphragm pocket 14 bottom can be adjusted to tune pressure and flow rate at which the diaphragm 16 may contact the lands 20. A height of the lands 20 within the diaphragm pocket 14 can be in approximately a range of about 0.4 millimeters to about 0.8 millimeters. Fluid flow through the emitter 10 via the inlet 24 and the outlet is discussed in greater detail below.

[0041] The emitter 10 can include a top cover 28 or seal that rests on top of the body 12 to prevent fluid from escaping therefrom and ensures that fluid flow moves progressively through the flow features without leaking or bypassing any regions. The top cover 28 may also include features that interface with the emitter 10 production line, enabling handling and conveyance. In the illustrated embodiment, the top cover 28 is shown as being spaced apart from the body 12, though this is done primarily for illustrative purposes and in use the top cover 28 may typically be coupled to the body 12 using any number of known coupling techniques, such as laser welding or ultrasonically welding the top cover 28 to the body 12.Atty. Dkt. No.: MIT 25861 PCT | 88212-425440 In some embodiments of the emitter body 12, clearances around hydraulic features can be sized to support both laser and ultrasonic welding. The top cover 28 can include a filter 30 therein for allowing water from a pump or another source to pass into the emitter 10.

[0042] In some embodiments, the emitter 10 can include an inlet 32 formed in the top cover 28 to help prevent entry of foreign particles into the emitter, thereby improving clogging performance thereof. For example, when the emitter 10 is disposed in a tube, e.g., a drip tube, with a particle-laden flow, the fluid can be located on the top cover 28, for instance above the center of the diaphragm 16. Rather than relying on geometric dimensions to keep contaminants out, which are ineffective and still allow silt, bacteria, and microbials, among other contaminants, to pass therethrough, the inlet 32 of the present embodiments can use hydrodynamic effects to filter out contaminants by entering through the gap in the filter seen in FIG.1. It will be appreciated that the designs of the inlet 64 of the present embodiments can leverage hydrodynamic effects for clog resistance.

[0043] Compactness of the emitter 10 can be achieved by decreasing an overall length of the emitter body 12. The overall length, in turn, can be driven, at least in part, by the size of the diaphragm pocket 14, length of the labyrinth 22, and / or clearances for top cover-emitter body welding, the latter of which is driven by manufacturing considerations. Further, the width of the emitter body 12 can be chosen such that the emitter 10 fits within typical tubing without creating significant obstruction to flow. This can allow the width, and therefore the diaphragm pocket 14 to be set to its maximum value. Commercial emitters comparable to emitter body 12 presented herein may typically have labyrinth lengths in the range of about 16 mm to about 24 mm. In contrast, in some embodiments, the labyrinth 60 of the present embodiments can have a length that is approximately in a range of about 9 mm to about 10 mm, or have a singular length that is approximately 0.4 inches, or approximately 0.376 inches (i.e., about 9.5504 mm long). It will be appreciated that the body 12 of the presently disclosed emitter can be approximately 0.3 inches to about 0.5 inches.

[0044] As noted above, the emitter 10 of the present embodiments distinguishes over conventional emitters due to its channel-less design in an effort to promote ease of production and increase clog-resistance. The emitter 10 can also maintain a circular diaphragm pocket 14 that is configured to receive a circular diaphragm 16 therein. It will be appreciated that the circular diaphragm 16 of the present embodiments can have axis symmetry to improve tractability of the diaphragm 16 when contacting the lands 20. The use of a circularAtty. Dkt. No.: MIT 25861 PCT | 88212-425440 diaphragm in lieu of other shapes, e.g., rectangular, square, and so forth, can be attributed to a perceived inability to modulate the junction between the diaphragm 16 and the diaphragm pocket 14 to achieve PC when using non-circular shaped diaphragms. It will be appreciated that in some embodiments, the dimensions and / or shape of the diaphragm pocket 14 can be dictated by, among other possible factors, a shape of the diaphragm, e.g., a circular shape thereof.

[0045] FIGS.2A-2B illustrate the operation of the emitter 10 via steps enumerated (1)-(5), with steps (1)-(3) illustrated in FIG.2A and steps (4)-(5) illustrated in a magnified portion of FIG.2A that is presented as FIG.2B. For the purpose of operation, in some embodiments, such as those shown in FIG.2A, the top cover 28 of the emitter 10 can rest on top of the body 12 to prevent fluid from escaping therefrom and ensures that fluid flow moves progressively through the flow features without leaking or bypassing any regions. As noted above, while the top cover 28 is shown as being spaced apart from the body 12, this is done primarily for illustrative purposes and in use the cover is typically coupled to the body 12.

[0046] At the start of operation, as shown at step (1), the fluid can enter the emitter 10 through the inlet 32 and / or filter(s) 30 in the top cover or seal 28. The water can enter the emitter 10 from and / or as directed by a pump (not shown) at a given pressure Pin, which is lower than activation pressure Pact. The water can flow towards the diaphragm pocket 14 to push and / or deflect the diaphragm 16 down towards and / or onto the lands 20, as indicated at step (2). From the diaphragm pocket 14, the fluid can be directed to enter the tortuous path of the labyrinth 22, as indicated at step (3). The zig-zag nature of the labyrinth 22 can promote turbulence or turbulent flow, which can dissipate energy, thereby losing pressure as it travels through the labyrinth 22. It will be appreciated that the turbulent flow can also occur in the diaphragm pocket 14.

[0047] Turning to FIG.2B, as indicated at step (4), the low-pressure fluid can enter the diaphragm pocket 14 below the diaphragm 16 via the transfer channel or transfer portal 34, in which a difference in hydraulic pressure above and below the diaphragm 16 can cause it to deflect towards the bottom of the diaphragm pocket 14. For example, as fluid enters the emitter 10, the fluid can travel above the diaphragm 16 to exert a downward pressure thereon. In turn, the diaphragm 16 can contact the lands 20. In some embodiments, the diaphragm 16 can deflect up to 1 millimeter, and / or approximately in a range of about 0.2 millimeters to about 0.8 millimeters. This can occur at or around the activation pressure at which point theAtty. Dkt. No.: MIT 25861 PCT | 88212-425440 pressure drop across the labyrinth (and therefore top and bottom of the diaphragm) is given by:

[0048] Δ^^ ൌ ^^^^^^^^ଶ^௧^ௗ, (1) where ^^^^௧^ௗis the desired flow rate of the emitter. In this manner, the labyrinth 22 can be central to supporting the pressure-compensating operation of the emitter. In step (5), the fluid can flow proximal to the diaphragm 16 and out of the outlet 26, with the outlet 26 being partially covered to create additional resistance for maintaining flow rate, as discussed below.

[0049] It will be appreciated that low-pressure channel-less emitters can include several design features that can impact the hydraulic capabilities of the emitter: labyrinth 22, flexible diaphragm 16, and an offset of the outlet 26. As noted above, fluid can enter through the inlet 32 at a gauge pressure ^^^^^^, which is directed into the labyrinth 22 where its pressure drops by ∆^^ due to hydraulic resistance. Flow then enters the diaphragm pocket 14 below the diaphragm 16 at a reduced pressure ^^2. The load on the flexible diaphragm 16 created by ∆^^ ൌ ^^^^^^ െ ^^2, can causes the diaphragm 16 to deflect towards the lands 20.

[0050] Similar to conventional PC emitters, the operating capabilities can be broken into two regions: pre-activation and post-activation. FIGS.3A-3C illustrate these two regions, which are discussed above with respect to steps (4) and (5) in the emitter 10, in greater detail. As shown, FIG.3A includes the emitter 10 with FIGS.3B and 3C illustrating flow of fluid from the transfer portal 34 into the diaphragm pocket 14 prior to the diaphragm 16 contacting the lands and post-contact, respectively. Pre-activation can occur when the diaphragm 16 has begun to deflect into the diaphragm pocket 14 and contact the lands 20, but has not yet overlapped the outlet 26 to allow fluid to flow to the outlet with low resistance 26 (^^^^^^<^^^^^^^^), as shown in FIG.3B., in which the fluid flows between the diaphragm 16 and the lands 20 to immediately exit the diaphragm pocket 14 via the outlet 26. Experimentally, this is shown by flow rate increasing with pressure at ^^ ∝ √^^^^^^. Activation can occur at ^^^^^^=^^^^^^^^ when the diaphragm 16 has contacted the lands 20 and spread over a part of the outlet due to sufficient fluid built up above the diaphragm 16. The built up fluid can exert a downward force that causes the diaphragm 16 towards the lands 20 and covers the outlet 26 enough to induce a resistance that causes flow to be constant, as shown in FIG.3C, in which the fluid must flow proximal to the diaphragm 16 and then beneath the diaphragm 16 to exit via the outlet 26.Atty. Dkt. No.: MIT 25861 PCT | 88212-425440 Experimentally, during post-activation, ^^^^^^>^^^^^^^^, there will be a near constant flow rate with increasing pressure, thereby establishing a PC region.

[0051] In some embodiments, a width of the outlet 26 can range from approximately 0.1 millimeters to about 2 millimeters, and / or have a width of about 0.5 millimeters. It will be appreciated that while the disclosure provides for a partial overlap of the diaphragm 16 with the outlet 26, in some embodiments, the diaphragm 16 can completely overlap with the outlet 26 and / or no portion of the diaphragm 16 may overlap with the outlet. Partial overlap of the diaphragm 16 with the outlet 26 can occur when a portion of a circumference of the diaphragm 16 can occlude a portion of the area of the outlet 26. In some embodiments, the diaphragm 16 can partly induces a resistance to the flow of fluid through the outlet 26.

[0052] Models of the diaphragm behavior can represent each hydraulic resistance as itsown pressure loss coefficient, ^^ ൌ ∆^^ଶ ^^^^^. During pre-activation (^^^^^^< ^^^^^^^^), the hydraulic resistances within the emitter 10 can include the labyrinth (^^^^^^^^) and the diaphragm cavity(^^^^^^^^). The labyrinth hydraulic can dominate as it encompasses the losses due to the sharp corners and narrow features inducing a turbulent behavior within high-velocity flow. The value of ^^^^^^^^ can be manipulated by adjusting the geometry of the labyrinth 22. The diaphragm cavity hydraulic resistance is much smaller as it only encompasses the friction losses in the region below the diaphragm 16. For pre-activation, equation 1.1 below can be used to relate ^^^^^^ to Q with ^^^^^^^^ and ^^^^^^^^ being constants. During post-activation (^^^^^^>^^^^^^^^), the hydraulic resistance of the diaphragm 16 covering the offset outlet, ^^^^, should be considered. This allows for equation 1.2 to be developed to describe post-activation ignoring minor losses in the system. ∆^^ = ^^^^^^ − ^^2 = ^^2(^^^^^^^^ + ^^^^^^^^) ^^^^^^ ^^^^^^ ≤ ^^^^^^^^ (1.1) ∆^^ = ^^^^^^ − ^^2 = ^^2(^^^^^^^^ + ^^^^) ^^^^^^ ^^^^^^ > ^^^^^^^^ (1.2) At least because ^^^^^^^^ and ^^^^^^^^ have been well accounted for purposes of pre-activation, the present disclosure optimizes post-activation and ^^^^ via adjusting position of the outlet 26 and / or a depth, h, of the lands 20, as discussed in greater detail below.

[0053] The pressure-compensating behavior of the low-pressure channel-less emitter 10 can come from the resistance ^^^^. ^^^^ is the hydraulic resistance produced in the diaphragmAtty. Dkt. No.: MIT 25861 PCT | 88212-425440 pocket 14 as fluid exits through a gap 36 between the diaphragm 16 and the outlet 26 due to a curve (^^^^^^) of the diaphragm 16. That is, the diaphragm is capable of being disposed in the diaphragm pocket 14 in a resting configuration and transition to a curved configuration after increased pressure is applied thereto. For example, during pre-activation, as shown in FIG. 3B, the outlet 26 can be uncovered allowing for there to be no resistance to flow other than ^^^^^^^^ and ^^^^^^^^ shown in equation 1.1. As ∆^^ increases, the diaphragm 16 can deflect more and will eventually contact the lands 20. As the contact length increases, more of the outlet 26 becomes covered, as shown in FIG.3C, leading to a smaller gap 36′ for fluid to exit through, thus increasing the hydraulic resistance to flow captured in ^^^^.

[0054] The design parameter ^^, shown in equation 1.3, below, is used to describe ^^^^ as it relates the contact length of the diaphragm 16 to the position of the outermost edge of the outlet 26 where flow can exit through. The conditions below (1.4, 1.5, 1.6), show the relationship between ^^ and ^^^^. ^^ ൌ ^^ା୰୭ାఢ^^ ≪ 1 െ ^^^^^^^^^^^^^^ ^^^^ ^^^^^^ℎ ^^^^^^^^ ^^ℎ^^^^ ^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^ െ ^^^^ ൌ 0 െ ^^^^^^< ^^^^^^^^ (1.4) ^^ → ^^^^^^^^^^െ ^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^ ^^^^ ^^^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^ െ ^^^^↑ െ ^^^^^^=^^^^^^^^(1.5) ^^ ^ 1 െ ^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^ ^^^^ ^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^ െ ^^^^ ൌ ^^^^^^ െ ^^ → 0 (1.6).

[0055] It will be appreciated that pressure-flow experimental results and analytical modeling of the diaphragm pocket 14 can be used to quantify ^^^^^^^^^^ to understand at which ^^ value activation occurs and flow rate becomes constant. By tuning design so that ^^ → ^^^^^^^^^^at a desired pressure and flow rate, designers can ensure that the emitter 10 will be pressure- compensating.

[0056] It will be appreciated that in Equation (1.3) above, c refers to a radius of the diaphragm 16, o refers to outlet position from the center of the diaphragm or contact patch 16, rorefers to radius of the outlet, and ^^ refers to a chamfer of the outlet 26, as shown in FIG. 4A. The partial coverage of the outlet 26 with the diaphragm 16 discussed above with respect to constant flow rate is shown in greater detail in FIGS.4B-4C. As shown, the diaphragm 16 can partially cover the outlet 26, which is offset from the center of the diaphragm, while contact between the diaphragm 16 and the pocket 14 changes with pressureAtty. Dkt. No.: MIT 25861 PCT | 88212-425440 exerted on the diaphragm. The chamfer 38 of the outlet, as shown in FIG.4C, may exist for manufacturing convenience or develop overtime due to progressive wear-and-tear. A size of the chamfer 38 is thus relatively small, and therefore the pressure-compensation of the emitter 10 is not strongly affected by the existence of such chamfers.

[0057] FIGS.5A-5C illustrate flow pressure curve results as a function of flow rates for outlet positions, o, of each of 0.5 millimeters (A), 1.0 millimeters (B), and 1.5 millimeters (C), and lands depths, h, of each of 0.4 millimeters, 0.6 millimeters, and 0.8 millimeters, respectively. It will be appreciated that outlet position is used as a factor herein due to the pressure of the emitter 10 being sensitive to a size of the outlet 26 that is uncovered. Each of the nine curves is shown in FIGS.5A-5C, with the objective being determining a value of pressure at which constant flow rate is achieved, e.g., pressure-compensating behavior starting at activation pressure, for the indicated outlet positions, o, and lands depths, h, withactivation assuming to have occurred at values of ^^ ≅ 0.95. The results of these pressurevalues for each combination of outlet position, o, and lands depth, h, are shown in FIG.6. These values are determined from the graphs of FIG.5A-5C based on the pressures at which the flow rate begins to level off and become constant. As shown, outlet positions, o, of 0.5 millimeters yield desirable activation pressures of 0.5 bar or less at each of the tested lands depths, h. Pressures of 0.5 bar or less are desirable at least because these activation pressures can allow the emitter 10 to operate with substantially lower pump sizes than conventional emitters, which can reduce system power consumption and cost. These low activation pressures may also allow farmers to operate longer fields conventional pumps, at least because lower pressure can be accommodated at the ends of drip tubes in which emitters are disposed. It will be appreciated that the outlet position of the emitter 10 of the present embodiments can be approximately in a range of about 0.1 millimeters to about 2.5 millimeters, and / or approximately in a range of about 0.4 millimeters to about 1.5 millimeters from the center of the diaphragm pocket 14 that is covered by the diaphragm 16.

[0058] A person having ordinary skill in the art will recognize that for the purposes of this disclosure, a “constant flow rate” can refer to pressure curves that have a slight downward slope, such as (A) and (B) in FIGS.5A-5C. For the purposes of this disclosure, the term “constant flow rate” can be read to encompass flow rate differences that differ by about 0.2 L / hour or less across the pressure curve. By way of example, FIG.7 illustrates a table that summarizes the geometry, activation pressures, maximum outlet coverage, ^^ value that wasAtty. Dkt. No.: MIT 25861 PCT | 88212-425440 reached, and the exponent, n, the last of which illustrates the flatness of the pressure curves. For the purposes of this disclosure, n values of 0.1 or less were deemed sufficient enough to characterize the pressure curves as flat, e.g., having a constant flow rate. As shown from the table in FIG.7, the geometries in rows 1, 4, and 7, which correlate to the top row of FIG.6, had the highest ^^ values, and therefore yielded the closest behavior to that of constant flow.

[0059] The emitters 10 of the present embodiments can consistently operate to pressure regulate in approximately a range between about 0.3 bar (4.35 psi) and about 2 bar (29 psi), while comparable conventional emitters can only pressure regulate up between 0.8 bar (11.6 psi) to 2 bar (51 psi). The wide pressure range can allow the emitter 10 to be used over a range of field sizes from small fields (e.g., approximately 800 ft. on side), to large fields, where high pump pressures are more likely to be operated where the low activation pressure can help reduce lifetime electricity / solar costs for affordable operation.

[0060] Examples of the above-described embodiments can include the following: 1. An irrigation emitter, comprising: a body having a volume defined between a pair of opposed walls, a pair of opposed sidewalls, and a top wall having a proximal-facing surface that is opposed to a bottom wall having a distal-facing surface, the body including: a diaphragm pocket recessed into the proximal-facing surface; a diaphragm disposed on a diaphragm seat such that a gap is formed between the diaphragm and the lands in a resting configuration, the diaphragm being configured to transition from the resting configuration to a curved configuration with application of increased pressure to minimize a size of the gap; a lands disposed within the diaphragm pocket, the lands having a first opening that defines an inlet and a second opening that defines an outlet, the outlet being offset from a center of the diaphragm, the lands being devoid of a channel; and a labyrinth in fluid communication with the diaphragm pocket, the labyrinth forming a tortuous path within the proximal-facing surface. 2. The emitter of example 1, wherein the emitter has an activation pressure as low as 0.3 bar. 3. The emitter of example 1 or example 2, wherein the diaphragm at least partially overlaps with the outlet in the curved configuration.Atty. Dkt. No.: MIT 25861 PCT | 88212-425440 4. The emitter of example 3, wherein the diaphragm completely cover the outlet in the curved configuration. 5. The emitter of any of examples 1 to 4, wherein the diaphragm pocket is circular. 6. The emitter of any of examples 1 to 5, wherein a shape of the diaphragm corresponds to a shape of the diaphragm pocket. 7. The emitter of any of examples 1 to 6, wherein the offset of the outlet from the center of the diaphragm is approximately in a range of about 0.4 millimeters to about 2.5 millimeters. 8. The emitter of example 7, wherein a depth of the lands is approximately in a range of about 0.4 millimeters to about 0.8 millimeters. 9. The emitter of any of examples 1 to 8, further comprising a shelf formed within the diaphragm pocket on which the diaphragm is disposed. 10. The emitter of any of examples 1 to 9, wherein the outlet further comprises a chamfered edge. 11. The emitter of any of examples 1 to 10, wherein the body receives the fluid from an irrigation system. 12. The emitter of any of examples 1 to 11, further comprising a transfer channel that connects the labyrinth with the inlet of the lands. 13. A method of controlling flow during irrigation, comprising: flowing a fluid into a body of an emitter, the body having a volume that is defined between a pair of opposed walls, a pair of opposed sidewalls, and a top wall having a proximal-facing surface that is opposed to a bottom wall having a distal-facing surface, wherein the fluid: passes onto a diaphragm disposed in a diaphragm pocket recessed into the proximal-facing surface, the diaphragm pocket having a first opening that defines an inlet and a second opening that defines an outlet; enters a labyrinth that is in fluid communication with the diaphragm pocket to flow through a plurality of recessed channels within the proximal-facing surface;Atty. Dkt. No.: MIT 25861 PCT | 88212-425440 exits the labyrinth into a portion of the diaphragm pocket disposed below the diaphragm; flows proximal to the diaphragm to deflect the diaphragm onto a lands disposed in the diaphragm pocket that extends proximally from the distal-facing surface; and flows through the outlet out of the body. 14. The method of example 13, further comprising adjusting a flow rate of the emitter without changing activation pressure by changing a depth of the lands or a position of the outlet. 15. The method of example 13 or example 14, further comprising increasing a hydraulic resistance of the emitter linearly with pressure above the activation pressure to set a constant flow rate. 16. The method of example 15, wherein increasing the hydraulic resistance further comprises offsetting a position of the outlet from a center of the diaphragm. 17. The method of example 16, wherein the offset of the outlet from the center of the diaphragm is approximately in a range of about 0.4 millimeters to about 2.5 millimeters. 18. The method of any of examples 13 to 17, wherein the diaphragm is deflected to at least partially overlap with the outlet. 19. The method of example 18, wherein at least a portion of a circumference of the diaphragm occludes at least a portion of the area of the outlet. 20. The method of any of examples 14 to 19, further comprising positioning the body within one or more tubes of an irrigation system such that it is in-line with a flow of fluid that passes through the one or more tubes. 21. The method of any of examples 14 to 20, wherein the fluid deflects the diaphragm into a curved configuration when the diaphragm contacts the lands to allow fluid to pass between the diaphragm and the lands to the outlet. 22. The method of any of examples 14 to 21, wherein the diaphragm pocket is devoid of a channel.Atty. Dkt. No.: MIT 25861 PCT | 88212-425440 23. A hydraulic system comprising: a pump configured to produce water using hydraulic pressure; a drip emitter of any of claims 1 to 12; and a tube for connecting the pump to a multiplicity of drip emitters.

[0061] One skilled in the art will appreciate further features and advantages of the disclosures based on the provided for descriptions and embodiments. Accordingly, the inventions are not to be limited by what has been particularly shown and described. To the extent the present disclosure includes illustrations and descriptions that include prototypes, bench models, or schematic illustrations of set-ups, a person skilled in the art will recognize how to rely upon the present disclosure to integrate the techniques, systems, devices, and methods provided into a product and / or method of irrigating, such as drip emitters. Further a person skilled in the art will appreciate how to manufacture emitters like those provided for herein using production methods such as milling of a homogenous material (e.g., aluminum or a plastic) via a milling machine.

[0062] Some non-limiting claims that are supported by the contents of the present disclosure are provided below.

Claims

Atty. Dkt. No.: MIT 25861 PCT | 88212-425440 What is claimed is:

1. An irrigation emitter, comprising: a body having a volume defined between a pair of opposed walls, a pair of opposed sidewalls, and a top wall having a proximal-facing surface that is opposed to a bottom wall having a distal-facing surface, the body including: a diaphragm pocket recessed into the proximal-facing surface; a diaphragm disposed on a diaphragm seat such that a gap is formed between the diaphragm and the lands in a resting configuration, the diaphragm being configured to transition from the resting configuration to a curved configuration with application of increased pressure to minimize a size of the gap; a lands disposed within the diaphragm pocket, the lands having a first opening that defines an inlet and a second opening that defines an outlet, the outlet being offset from a center of the diaphragm, the lands being devoid of a channel; and a labyrinth in fluid communication with the diaphragm pocket, the labyrinth forming a tortuous path within the proximal-facing surface.

2. The emitter of claim 1, wherein the emitter has an activation pressure as low as 0.3 bar.

3. The emitter of claim 1, wherein the diaphragm at least partially overlaps with the outlet in the curved configuration.

4. The emitter of claim 3, wherein the diaphragm completely cover the outlet in the curved configuration.

5. The emitter of claim 1, wherein the diaphragm pocket is circular.

6. The emitter of claim 1, wherein a shape of the diaphragm corresponds to a shape of the diaphragm pocket.

7. The emitter of claim 1, wherein the offset of the outlet from the center of the diaphragm is approximately in a range of about 0.4 millimeters to about 2.5 millimeters.

8. The emitter of claim 7, wherein a depth of the lands is approximately in a range of about 0.4 millimeters to about 0.8 millimeters.Atty. Dkt. No.: MIT 25861 PCT | 88212-425440 9. The emitter of claim 1, wherein the outlet further comprises a chamfered edge.

10. A method of controlling flow during irrigation, comprising: flowing a fluid into a body of an emitter, the body having a volume that is defined between a pair of opposed walls, a pair of opposed sidewalls, and a top wall having a proximal-facing surface that is opposed to a bottom wall having a distal-facing surface, wherein the fluid: passes onto a diaphragm disposed in a diaphragm pocket recessed into the proximal-facing surface, the diaphragm pocket having a first opening that defines an inlet and a second opening that defines an outlet; enters a labyrinth that is in fluid communication with the diaphragm pocket to flow through a plurality of recessed channels within the proximal-facing surface; exits the labyrinth into a portion of the diaphragm pocket disposed below the diaphragm; flows proximal to the diaphragm to deflect the diaphragm onto a lands disposed in the diaphragm pocket that extends proximally from the distal-facing surface; and flows through the outlet out of the body.

11. The method of claim 10, further comprising adjusting a flow rate of the emitter without changing activation pressure by changing a depth of the lands or a position of the outlet.

12. The method of claim 10, further comprising increasing a hydraulic resistance of the emitter linearly with pressure above the activation pressure to set a constant flow rate.

13. The method of claim 12, wherein increasing the hydraulic resistance further comprises offsetting a position of the outlet from a center of the diaphragm.

14. The method of claim 13, wherein the offset of the outlet from the center of the diaphragm is approximately in a range of about 0.4 millimeters to about 2.5 millimeters.

15. The method of claim 10, wherein the diaphragm is deflected to at least partially overlap with the outlet.

16. The method of claim 15, wherein at least a portion of a circumference of the diaphragm occludes at least a portion of the area of the outlet.Atty. Dkt. No.: MIT 25861 PCT | 88212-425440 17. The method of claim 16, further comprising positioning the body within one or more tubes of an irrigation system such that it is in-line with a flow of fluid that passes through the one or more tubes.

18. The method of claim 10, wherein the fluid deflects the diaphragm into a curved configuration when the diaphragm contacts the lands to allow fluid to pass between the diaphragm and the lands to the outlet.

19. The method of claim 10, wherein the diaphragm pocket is devoid of a channel.

20. A hydraulic system comprising: a pump configured to produce water using hydraulic pressure; a drip emitter of claim 1; and a tube for connecting the pump to a multiplicity of drip emitters.

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