Patent Publication Number: US-2020288653-A1

Title: Drip emitter having membrane with a non-planar portion protruding into regulating chamber recess

Description:
RELATED APPLICATIONS 
     This is a Bypass Continuation of International Application No. PCT/IB2018/059840 filed Dec. 10, 2018 and published as WO 2019/116206A2. Priority is claimed to. U.S. Provisional Patent Application No. 62/597,701, filed Dec. 12, 2017. The contents of the aforementioned applications are incorporated by reference in their entirety. 
    
    
     BACKGROUND 
     Membranes can be used for various purposes in irrigation drip emitters in connection to waterways formed in the emitter. For example, a membrane may be used for controlling the flow rate of water discharged by the emitter, for sealing between parts of the emitter, for defining valves in the emitter and/or for defining flow-paths within the emitter. 
     In control of flow rate, for example, the membrane operates to control liquid flow out of the emitter so that it is substantially independent of pressure at an inlet of the emitter for a range of pressures typically encountered in irrigation applications. For this purpose, the membrane is normally located between inlet and outlet waterways of the emitter and in response to increase in pressure of the entering water undergoes distortion that operates to increase resistance to liquid flow through and out of the emitter. 
     U.S. Pat. No. 4,210,287 discloses an emitter unit provided with a resiliently flexible membrane, which is releasably retained within a body member so as to serve a double function. On the one hand, whilst being exposed to the irrigation flow pressure in the conduit to serve in exercising differential pressure control, and, on the other hand, to define, with respect to a flow restricting waterway groove formed in the body member, a flow-restricting waterway flow-path. 
     Provision of drip emitters that are less expensive is desirable and one way of providing same may be to design a drip emitter from a single part, which thus requires less or substantially no assembly steps to be completed for use. In particular, provision of such a single part drip emitter may be beneficial in drip emitters that are made from different type materials, such as pressure regulated drip emitters that typically include a plastic body and an elastic membrane for assisting in the pressure regulation. 
     SUMMARY 
     The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools and methods which are meant to be exemplary and illustrative, not limiting in scope. 
     In an embodiment there is provided a flexible membrane for a drip emitter, wherein the membrane in a non-stressed or non-flexed state comprises a non-planar portion. 
     Such membrane may be suitable for use in drip emitters formed in a bi-component molding process where the membrane may be formed from a material that is different to material(s) in remaining parts of the emitter. 
     Preferably, such drip emitters may be formed form two parts where the membrane is formed in a first part (possibly within a frame of the first part) and the other second part may be formed with a recess that when overlaid by the membrane forms a regulating chamber of the emitter. 
     Possibly, the non-planar portion comprises a generally free-form shape and/or it comprises a generally plane curve shape, preferably a smooth plane curve shape. 
     In an embodiment there is also or in addition provided a drip emitter comprising body and flap members connected at a hinge, the body and/or flap members being arranged to be pivoted about the hinge towards each other to form an operative state of the emitter suitable for performing drip irrigation, wherein when first pivoting the body and/or flap members one towards the other to form the operative state, and then leaving the members free to flex back away from each other to reach a relative open state; an included angle formed between the two members in the relative open state is configured to be less than about 35 degrees, and preferably less than about 30 degrees. 
     In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the figures and by study of the following detailed descriptions. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Exemplary embodiments are illustrated in referenced figures. It is intended that the embodiments and figures disclosed herein are to be considered illustrative, rather than restrictive. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying figures, in which: 
         FIG. 1  schematically shows a drip emitter in accordance with an embodiment of the present invention in an open state; 
         FIGS. 2A and 2B  schematically show a closed operative state of the drip emitter of  FIG. 1 , from respective bottom and upper sides; 
         FIG. 3  schematically shows a cross sectional view of a drip emitter generally similar to that in  FIG. 1  in its open state; 
         FIGS. 4A and 4B  schematically show cross sectional views, respectively, of a regulating chamber of an embodiment of a drip emitter of the invention and a molding step for forming a membrane embodiment defining said chamber; 
         FIGS. 5A to 5C  schematically show cross sectional views of various membrane embodiments of the invention; 
         FIGS. 6A and 6B  schematically show, respectively, an embodiment of a drip emitter and a membrane embodiment possibly used in this drip emitter; and 
         FIGS. 7A and 7B  schematically show a cross sectional view of a hinge area of an embodiment of a drip emitter generally similar to those in  FIG. 1 to 3 or 6  in respective closed and relative open states. 
     
    
    
     It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated within the figures to indicate like elements. 
     DETAILED DESCRIPTION 
     Attention is first drawn to  FIGS. 1, 2A and 2B  illustrating an embodiment of a drip emitter  10  of the invention in respective open ( FIG. 1 ) and closed ( FIGS. 2A and 2B ) states. Emitter  10  has a body  12  and a flap  14  that are both connected at a hinge  17  to form a housing  7  of the emitter. Body  12  and flap  14  include respective body and flap regions  52 ,  51  on opposing sides of hinge  17 —and pivoting of flap  14  and/or body  12  towards each other about hinge  17  forms an operative closed state of the emitter suitable for use. 
     In the operative state, body region  52  and flap region  51  are brought closer together to form an abutment or close to abutment relationship. An emitter may be secured in such closed operative state by respective fixation means  37  located both on flap  14  and body  12 , which are configured to engage each other to maintain/secure the emitter in its closed operative state. 
     Body  12  may be formed by injection molding from Polyolefin materials typically used in production of drip emitters, such as preferably Polyethylene (PE). Flap  14  may include a frame  16  formed possibly from similar, preferably identical, material as body  12 , and possibly molded together with body  12  during its production to optionally form hinge  17  as a living hinge. 
     In accordance with an aspect of the invention, emitter  10  may include a diaphragm or membrane  18  located within frame  16 . Membrane  18  may preferably be formed within frame  16  during the production of the emitter by injection molding, preferably from a more flexible and/or elastic material than body  12 , possibly from a thermoplastic elastomer (TPE). In various embodiments of the invention, the frame may be injected prior to the membrane that is then molded thereupon; or the membrane may be injected prior to the frame that is then molded thereupon, or the frame and membrane may be molded substantially together at the same time. 
     The emitter parts/elements, e.g., membrane, body and flap—may be formed in the same mold apparatus by injecting each time one or more of the parts into cavities within the mold. Possibly such mold may include moving segments forming during a molding procedure various cavities into which molten material forming the various emitter parts/elements may be injected. Thus, a molding technology possibly utilized for forming at least certain emitter embodiments of the invention—may be considered as bi-component or multi-component molding technology—where several components/parts of an emitter may be molded in a single mold apparatus. In some cases, also single component molding technology may be used, where a mold may be designed to include a single cavity into which all parts of the emitter may be injected. Martials suitable for such single component option may include TPE materials e.g. TPE of SEBS type. 
     Emitter  10  in its closed operative state includes an outer side  13  (see  FIG. 2B ) that is configured to attach possibly by heat bonding (or the like) to an inner face of an irrigation pipe (not shown); and an inner side  15  (see  FIG. 2A ) that is configured to face into the pipe to be exposed to pressurized liquid and/or substances flowing through the pipe. 
     The emitter&#39;s outer side  13  in this optional example includes an exit pool  20  and a labyrinth  22 . Labyrinth  22  is here arranged to receive liquid entering the emitter via an inlet  24 , in this example in the form of a filter, formed in inner side  15 . The liquid entering the emitter passes via an entry  26  to outer side  13  in order to flow onwards downstream via labyrinth  22 . 
     Labyrinth  22  has an ending  28  via which liquid can pass back downwards into a recess  32  (see recess  32  e.g. in  FIGS. 1 and 3 ) that forms with membrane  18  (in a closed operative state of the emitter) a regulating chamber  34  of the emitter (see, e.g., regulating chamber  34  in  FIG. 4A ). From regulating chamber  34 /recess  32 —the liquid flows back upwards via an exit  30  of the emitter into exit pool  20  and from there onwards downstream to exit the pipe (via an aperture, slit, or the like) in order to transfer substances to an ambient environment (such as soil or the like) outside of such pipe. Such transfer of substances (e.g. liquids nutrients or the like) may be for irrigation purposes or any other suitable required purpose. 
     Although flap  14  is illustrated herein as including, inter alia, elements such as membrane  18  and frame  16 —in various embodiments, flap  14  may be arranged to include additional elements of the emitter. For example, flap  14  may be configured to include also inlet  24  and/or possibly substantially most of the emitter&#39;s elements forming, belonging and/or associated to the emitter&#39;s inner side  15 . In addition, hinge  17  herein illustrated as extending along a longitudinal side extension  19  of the emitter, may be arranged to extend along a shorter lateral extension  21  of the emitter (see extensions  19 ,  21  indicated in  FIG. 2A ). 
     Attention is additionally drawn to  FIGS. 3, 4A and 4B . In  FIG. 3  emitter  10  is illustrated in its open non-operative state (as in  FIG. 1 ) prior to being urged to its closed operative state seen in  FIG. 2  by rotating flap  14  and/or body  12  about hinge  17 . Recess  32  may be bound by a raised rim  36  (see also  FIG. 1 ) that is formed about its perimeter and that extends above body region  52 .  FIG. 4A  is a section of the emitter in its closed operative state illustrating the emitter&#39;s regulating chamber  34  that is formed by membrane  18  being pressed against rim  36  to overlay/seal recess  32 . 
     The embodiment of membrane  18  illustrated in  FIGS. 3, 4A and 4B  is seen including a possible convex bulging portion  38 , which in the closed operative state of the emitter (see  FIG. 4A ) is configured to slightly bulge into recess  32 .  FIG. 4B  provides a view of a mold segment  40  that may be used for forming the membrane embodiment illustrated in  FIGS. 3 and 4A . 
     Mold segment  40  seen in  FIG. 4B  may be a segment that can be used during an injection molding process of emitter  10 . Mold segment  40  may possibly be a movable mold segment that may be moved to a position within a mold forming the emitter—after a prior injection molding phase in which frame  16  surrounding the membrane was formed by injection molding. In certain cases, mold segment  40  may be a static mold segment as in the illustrated examples—where an opposing mold segment (not shown) may be movable to form the cavity for the membrane. 
     It is noted that other partitions, mold parts (and the like) may typically be used in a molding process forming membrane  18 , however these have not been illustrated in  FIG. 4B . In addition, mold segment  40  may extend about further portions surrounding a cavity in which membrane  18  illustrated in  FIG. 4B  is formed by injection molding. 
     Mold segment  40  includes a face  42  that at least a portion of the molten material forming membrane  18  can meet during the injection molding phase of the membrane. Face  42  as here illustrated includes a concave portion and molten material filling a mold cavity including face  42  will be urged to form convex portion  38  of the membrane as it meets the concave area of face  42 . Thus, membrane  18  in its normal unstressed state after injection molding may be configured to embody a geometry including convex portion  38 . 
     With attention drawn back to  FIG. 4A , membrane  18  in the closed operative state of the emitter is accordingly seen including convex portion  38  slightly bulging into recess  32  as it forms the emitter&#39;s regulating chamber  34 . It is noted that membrane  18  in the state seen in  FIG. 4A  may be slightly stressed away from cavity  32  due its possible bearing pressed engagement against raised rim  36  that surrounds cavity  32 . In any case, in at least certain emitter/membrane embodiments—the bulging condition of membrane  18  into cavity  32  may be due to membrane being urged to maintain and/or re-assume its unstressed state that in certain cases includes convex/bulging portion  38 . 
     The pressing engagement of the membrane against raised rim  36  may be required in certain embodiments in order to seal the periphery of the regulating chamber against rim  36  so that the regulating chamber can function properly for regulating the flow of liquid exiting emitter  10 . 
     Such pressing engagement of membranes that may be required in some cases for effectively sealing a cavity of a regulating chamber, may result in some membranes being urged to possibly flex away from such cavity. In membranes lacking a convex portion (such as portion  38 ), this may possibly result in such membranes being urged to flex to a position where then may even bulge away from their respective cavities to an extent schematically illustrated by the ‘dashed lines’ in  FIG. 4A . 
     If this was to occur, the effectiveness of such membranes in regulating liquid flow through an emitter may be harmed, since effective flow regulation typically occurs as a distance D, e.g., decreases between the membrane and a face of cavity  32  adjacent exit  30  as the membrane flexes inwards due to rise in pressure liquid in the pipe. Thus, membranes starting off from a position as that generally illustrated by the ‘dashed lines’ in  FIG. 4A , may initially be required to flex back towards a state where they start to bulge into cavity  32  before effective regulation can commence. 
     In at least certain embodiments of the invention, the slight natural bulging condition of membrane  18  into cavity  32  due to convex portion  38  may assist in mitigating such outcome as discussed. Since also in cases where the membrane may be urged to flex away from the cavity, the pre-defined bulging of the membrane (in its substantial unstressed condition) into cavity  32 , may position the membrane at a better starting point for early entry into effective liquid flow regulation upon start of rise in liquid pressure in the pipe. 
     With attention drawn to  FIGS. 5A to 5C  various membrane embodiments are shown possibly used in drip emitters generally similar to those in e.g.  FIGS. 1 and 2 . In  FIGS. 5A and 5B , the membranes are seen having varying thickness in convex portion  38  as it bulges towards an apex  47  of the membrane configured to be placed generally above exit  30  of the emitter in the emitter&#39;s operative state. In  FIG. 5A  the thickness appears to increase while in  FIG. 5B  to decrease as convex portion  38  reaches closer to apex  47 . 
     In  FIG. 5C , a membrane embodiment is seen including an upper generally flattened area  45  generally at the membrane&#39;s apex  47 . Such flattened area  45  in certain cases, may assist in facilitating effective pressure regulation in a drip emitter including such membrane, by defining generally two parallel planes, one area  45  and the other a region  77  adjacent exit  30  of the emitter—between which outward flow regulation is controlled as distance D decreases or increases. 
     Attention is drawn to  FIGS. 6A and 6B  illustrating an embodiment of a drip emitter  100  that may differ from emitter  10  in absence of the raised rim around recess  32  upon which the sealing of the recess in the operative state of emitter  10  may possibly occur. Emitter  100  may further differ from the former emitter (emitter  10 ) in inclusion of a membrane embodiment  180  that may comprise a raised peripheral wall  360  on its side that faces recess  32  in the emitter&#39;s operative state. Peripheral wall  360  may be arranged to project up from an otherwise generally planar face  361  of the membrane. Thus, in an aspect of the invention, sealing of the regulating chamber of emitter  100  may be embodied by peripheral wall  360  of membrane  180  being arranged to press against a surface possibly constituting and/or including body region  52  that surrounds recess  32  in the emitter&#39;s operative state. 
     In certain embodiments (not shown) emitter  100  may include a raised rim (such as rim  36 ) around its recess  32  upon which the sealing of the recess in the operative state of emitter  10  may possibly occur, and such sealing in emitter  100  may include the membrane&#39;s peripheral wall  360  being arranged to at least partially press against the raised rim. 
     Attention is drawn to  FIGS. 7A and 7B  each illustrating a similar cross sectional view of an emitter embodiment (generally similar e g to emitters  10  or  100 ). These views illustrate an area of the emitter adjacent hinge  17 . In  FIG. 7A  the emitter is seen in its closed operative state where e.g. regions  51 ,  52  are placed adjacently each other, and in  FIG. 7B  the emitter is seen in a relative slightly open state where e.g. the regions  51 ,  52  are slightly spaced apart about hinge  17 . Also seen and indicated in these figures (as also in  FIG. 1 ) are body and flap depressions  62 ,  61  formed, respectively, on opposing sides of hinge  17  adjacent body and flap regions  52 ,  51 . 
     In the view of  FIG. 7A  respective planes  71 ,  72  extending from and/or including regions  51 ,  52  are marked by the dashed lines. Preferably, planes  71 ,  72  extend and/or include areas of regions  51 ,  52  most proximal to hinge  17 , possibly adjacent depressions  61 ,  62 ; to thus provide a measure of an angle α representative of an opening angle exhibited at or adjacent to the hinge  17 . In  FIG. 7A  these planes  71   72  are seen generally parallel to each other. Such condition may be generally representative of a closed operative state of an emitter. In the view of  FIG. 7B  these respective ‘dashed’ marked planes  71 ,  72  are seen spaced apart about hinge  17  forming an angle α greater than “zero”. 
     Hinge  17  is designed to guide flap  14  and body  12  towards each other to form the emitter&#39;s operative closed state where, inter alia, regions  51 ,  52  are placed in abutting or near abutting relation close together as seen in  FIG. 7A . In this operative state, the flap and body are configured to, respectively, place membrane  18  in pressing engagement against rim  36  (as in emitter  10 ) and/or peripheral wall  360  of membrane  180  in pressing engagement against an area surrounding recess  32  (as in emitter  100 )—in order to seal the emitter&#39;s regulating chamber  34 —while the closed operative state can be maintained by the emitter&#39;s fixation means  37 . 
     In certain embodiments, the emitter in areas at or adjacent hinge  17 —may be configured once forming the closed operative state—to impose limited (or substantially no) moment forces M acting to urge the flap and body away from each other about the hinge towards a more open state. 
     In the illustrated embodiments, such moment forces M if exceeding certain values may act e.g. to distort/bias slightly the emitter&#39;s body and flap away from each other (while flap and body are maintained fixed together by fixation means  37 ). Such distortion/bias, inter alia, also in regions  51 ,  52 —may possibly reduce the pressing engagement between membrane  18  and rim  36  (in emitter  10 ) and/or wall  360  against area around recess  32  (in emitter  100 ) and consequently possibly harm the sealing of the regulating chamber  34  that may be required for proper pressure regulation of the emitter. 
     Such formation of moment forces M may at least partially be mitigated in certain embodiments, by hinge  17  being designed to undergo relative large plastic deformations while flap  14  and/or base  12  are first pivoted towards each other about the hinge. This first pivoting of the base and/or flap towards each other may be from a state/condition of the emitter (such as that seen in  FIG. 3 ) representative of the emitter after e.g. the base, flap and membrane have been molded by injection molding. This first pivoting may be formed within the mold prior to extraction of the molded emitter from the mold. In some cases, this stage of first pivoting may be performed after the molded emitter exited the mold in the state generally seen in  FIG. 3 . 
     Relative large plastic deformations occurring within the hinge—may consequently limit presence of substantial elastic forces within (or in the region of) the hinge that may contribute to formation of the discussed moment forces M. Such hinge configuration designed to undergo large plastic deformation may consequently reduce likelihood of harm to the sealing of the regulating chamber  34 . 
     In some embodiments (possibly combinable with the former), an emitter with a hinge region  17  designed for reduced formation of the discussed moment forces M may be defined by the following test. An emitter with no prior pivoting of the flap and/or base about hinge may first be urged to a position generally similar to that seen in  FIG. 7A  where the regions  51 ,  52  generally abut or are in close abutment relation. In the discussed test, the urging of the flap and/or base about the hinge may be executed by applying forces F acting to urge this closing movement at a distal location to the hinge possibly adjacent areas of the emitter proximal to where cooperating members of the fixations means are present on the body and flap. Without having the fixation means  37  fix the base to flap, these both elements are then left to flex back away from each other to a position generally illustrated in  FIG. 7B  resulting in angle α formed between planes  71 ,  72 . The biasing force urging this flexing of the base and flap away from each other may be substantially due to the moment forces M present in the hinge. 
     In tests performed by the inventors it has been found that an emitter exhibiting a moment force M less likely to undermine the sealing of the regulating chamber—is observed to form an angle α less than about 35 degrees and preferably less than about 30 degrees. The above angle criteria of a may be taken as representative to the amount of plastic deformation subjected to hinge  17  and hence the residual elastic deformation left in the hinge  17  after such plastic deformation. 
     In some embodiments (possibly combinable with one or more of the former hinge embodiments), relative small formation of the above discussed moment forces M may be defined by a hinge  17  having a minimal thickness H generally less than about 0.4 millimeter and preferably larger than about 0.15 millimeters. See thickness H indicated in the encircled section at the lower right-hand side of  FIG. 3 . 
     In yet a further embodiment (possibly combinable with one or more of the former hinge embodiments), presence of the depressions  61 ,  62  adjacent the hinge may assist in improving placement of the regions  51 ,  52  adjacent to each other in the closed operative state of the emitter. These depressions  61 ,  62  identifiable also in the emitter&#39;s closed state, space the regions  51 ,  52  from hinge  17  and hence limit the moment forces M that may arise due to materials adjacent to the hinge being made to meet each other. In the shown example, these depressions  61 ,  62  are shown on both sides of the hinge  17 , however in certain embodiments, presence of only one of the depressions  61  or  62  may be sufficient in mitigating the discussed formation of moment forces M and consequently the mentioned outcome of harm to the sealing of the regulating chamber. 
     In the description and claims of the present application, each of the verbs, “comprise” “include” and “have”, and conjugates thereof, are used to indicate that the object or objects of the verb are not necessarily a complete listing of members, components, elements or parts of the subject or subjects of the verb. 
     Furthermore, while the present application or technology has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and non-restrictive; the technology is thus not limited to the disclosed embodiments. Variations to the disclosed embodiments can be understood and effected by those skilled in the art and practicing the claimed technology, from a study of the drawings, the technology, and the appended claims. 
     In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. 
     The present technology is also understood to encompass the exact terms, features, numerical values or ranges etc., if in here such terms, features, numerical values or ranges etc. are referred to in connection with terms such as “about, ca., substantially, generally, at least” etc. In other words, “about 3” shall also comprise “3” or “substantially perpendicular” shall also comprise “perpendicular”. Any reference signs in the claims should not be considered as limiting the scope. 
     Although the present embodiments have been described to a certain degree of particularity, it should be understood that various alterations and modifications could be made without departing from the scope of the invention as hereinafter claimed.