Abstract:
A system including: (a) a pipe having an aperture providing fluid communication between inner and outer pipe surfaces; (b) a cylindrical drip emitter disposed within the pipe, including: an emitter body having an outer facing having a generally convex contour adapted in generally complementary fashion to a concave contour of the inner pipe surface, the outer facing secured to the inner surface; a liquid inlet section adapted to receive a liquid from within the pipe, and to deliver the liquid, via the aperture, to the outer facing; a pressure-reducing section disposed in fluid communication with the liquid inlet section; functionally active sections including the pressure-reducing section, the liquid inlet section, the functionally active sections disposed within, and longitudinally defining, a position of a longitudinal segment of the body; and at least one functionally passive section, disposed on the outer facing, within the longitudinal segment; and (c) a liquid flow path fluidly connecting between the liquid inlet section and the passive section, via the pressure-reducing section, and between the passive section and an ambient environment, via the first aperture, wherein the first aperture is situated within longitudinal bounds of the longitudinal segment, and radially aligned with the functionally passive section disposed within the longitudinal segment.

Description:
FIELD AND BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to drip irrigation emitters, and, more particularly, to compact cylindrical-type drip irrigation emitters. 
         [0002]    Drip irrigation is a particularly efficient method of irrigating, particularly in arid environments. Water is slowly applied directly to the soil, enabling the water to be quickly absorbed, whereby losses due to evaporation or to run off are reduced. Drip irrigation systems may be utilized to irrigate a particular area around a plant. This further reduces water consumption and also reduces weed growth. 
         [0003]    Market forces are continually demanding improved performance and improved cost efficiencies for drip irrigation systems. While a plethora of drip emitter types and species have been developed to meet various needs of the consumer, the present inventor has recognized a need for further improving the cost efficiency of cylindrical drip irrigation emitters. 
       SUMMARY OF THE INVENTION 
       [0004]    According to the teachings of the present invention there is provided a liquid delivery system including: (a) a pipe having an inner surface and an outer surface, and at least a first aperture providing fluid communication between the surfaces; (b) a drip emitter disposed within the pipe, the emitter including: (i) an emitter body having an inner facing and an outer facing, the outer facing having a generally convex contour adapted in generally complementary fashion to a concave contour of the inner surface, the outer facing secured to the inner surface, the body having a length L; (ii) a liquid inlet section adapted to receive a liquid from within the pipe, and to deliver the liquid to the outer facing; (iii) at least one pressure-reducing section disposed in fluid communication with the liquid inlet section; (iii) functionally active sections including at least the pressure-reducing section and the liquid inlet section, the functionally active sections having a total length La, the functionally active sections disposed within, and longitudinally defining, a position of at least one longitudinal segment of the emitter body; and (iv) at least one functionally passive section, disposed on the outer facing, at least partially within the longitudinal segment; and (c) a liquid flow path fluidly connecting between the liquid inlet section and the passive section, via the pressure-reducing section, and between the passive section and an ambient environment, via the first aperture, wherein the first aperture is situated within longitudinal bounds of the longitudinal segment, and radially aligned with a portion of the functionally passive section disposed within the longitudinal segment; the outer facing spanning, in at least one location, an arc corresponding to an angle of at least 140° of the inner surface of the pipe. 
         [0005]    According to further features in the described preferred embodiments, the functionally active sections include a pressure-controlling section. 
         [0006]    According to further features in the described preferred embodiments, the functionally active sections consist of the pressure-reducing section, the liquid inlet section, and a pressure-controlling section. 
         [0007]    According to further features in the described preferred embodiments, the functionally active sections consist of the pressure-reducing section and the liquid inlet section. 
         [0008]    According to still further features in the described preferred embodiments, a length ratio of La to L of the emitter body is at least 0.60 or at least 0.65. 
         [0009]    According to still further features in the described preferred embodiments, this length ratio is at least 0.70, at least 0.75, at least 0.78, at least 0.80, at least 0.82, or at least 0.85. 
         [0010]    According to still further features in the described preferred embodiments, the inner facing has a diameter D, wherein an aspect ratio of the diameter D to length L is at least 0.25, at least 0.30, or at least 0.34. 
         [0011]    According to still further features in the described preferred embodiments, the outer facing spans, in at least one location, an arc corresponding to an angle of at least 180°, at least 225°, or at least 270° of the inner surface. 
         [0012]    According to still further features in the described preferred embodiments, the outer facing spans, in at least one location, an arc corresponding to an angle of 360° of the inner surface. 
         [0013]    According to still further features in the described preferred embodiments, the emitter body is generally cylindrical. 
         [0014]    According to still further features in the described preferred embodiments, the emitter body is generally cylindrical over all of length La. 
         [0015]    According to still further features in the described preferred embodiments, the emitter body is generally cylindrical over all of length L. 
         [0016]    According to still further features in the described preferred embodiments, the pressure-reducing section includes at least one labyrinth channel. 
         [0017]    According to still further features in the described preferred embodiments, the distance between a first end of the emitter body and a proximal end of the functionally active sections disposed proximally to the first end, is less than 9 mm, less than 7 mm, less than 5 mm, or less than 4 mm. 
         [0018]    According to still further features in the described preferred embodiments, the functionally active sections are substantially longitudinally continuous with respect to the body. 
         [0019]    According to still further features in the described preferred embodiments, the pipe has at least one additional aperture disposed therethrough, the additional aperture situated within length L, but longitudinally outside of the longitudinal segment of the drip emitter. 
         [0020]    According to still further features in the described preferred embodiments, the liquid inlet section includes a filtration section. 
         [0021]    According to still further features in the described preferred embodiments, the outer surface of the pipe has at least one protrusion indicating a radial alignment of the emitter within the pipe. 
         [0022]    According to still further features in the described preferred embodiments, the emitter has at least one alignment protrusion in the outer facing, the alignment protrusion at least partially protruding into the pipe. 
         [0023]    According to still further features in the described preferred embodiments, the outer surface of the pipe has at least one mark, groove, or other external feature indicating a radial alignment of the emitter within the pipe. 
         [0024]    According to still further features in the described preferred embodiments, an opening passes through the emitter body, whereby the inner facing and the outer facing are in fluid communication, the liquid inlet section adapted to receive the liquid from within the pipe, via the inner facing, and to deliver the liquid, via the opening, to the outer facing. 
         [0025]    According to still further features in the described preferred embodiments, the functionally passive section is disposed completely within the longitudinal segment. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    The invention is herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. Throughout the drawings, like-referenced characters are used to designate like elements. 
           [0027]    In the drawings: 
           [0028]      FIG. 1  is a side view of a drip irrigation emitter of the prior art; 
           [0029]      FIG. 2  is a perspective view of the drip irrigation emitter of  FIG. 1 , disposed within a partially transparent irrigation pipe; 
           [0030]      FIG. 3  provides a perspective view of a drip irrigation emitter according to an exemplary embodiment of the present invention; 
           [0031]      FIG. 4  is an axially cut-open view of the drip irrigation emitter of  FIG. 3 , disposed within a partially transparent irrigation pipe; 
           [0032]      FIG. 5  provides a second perspective view of the drip irrigation emitter of  FIG. 3 ; 
           [0033]      FIG. 6  is a side view of the inventive drip irrigation emitter of  FIG. 3 ; 
           [0034]      FIG. 7  is a perspective view of the inventive drip irrigation emitter of  FIG. 3 , disposed within a partially transparent irrigation pipe; 
           [0035]      FIG. 8  is a perspective view of another exemplary embodiment of the inventive drip irrigation emitter, disposed within a partially transparent irrigation pipe; 
           [0036]      FIG. 9  provides a perspective view of a pressure-controlling drip irrigation emitter, according to another exemplary embodiment of the present invention; 
           [0037]      FIG. 10  is a perspective view of another exemplary embodiment of the inventive drip irrigation emitter, the outer surface of the emitter body having an arc or contour of about 160°; 
           [0038]      FIG. 11A  is a perspective view of another exemplary embodiment of the inventive drip emitter, disposed within a within a non-cylindrical irrigation pipe; 
           [0039]      FIG. 11B  is a wire-rim drawing of the drip irrigation emitter of  FIG. 11A , in which the outer surface of the emitter body has a contour of about 250°; 
           [0040]      FIG. 12A  is a generally axial perspective view of another exemplary embodiment of the inventive drip emitter, having alignment protrusions disposed in an outer facing of the emitter body; and 
           [0041]      FIG. 12B  is another perspective view of the drip emitter of  FIG. 12A , disposed within a partially transparent pipe. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0042]    The principles and operation of the cylindrical drip irrigation emitter according to the present invention may be better understood with reference to the drawings and the accompanying description. 
         [0043]    Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting. 
         [0044]    With reference now to the drawings,  FIG. 1  is a side view of a drip irrigation emitter  100  of the prior art. Drip irrigation emitter  100  is a cylindrical emitter, adapted to be bonded to an irrigation pipe  210 , shown in  FIG. 2 . Emitter  100  includes a liquid inlet section  120 , a labyrinth channel  130 , and a liquid transfer section  140 . 
         [0045]    Liquid inlet section  120  fluidly communicates with labyrinth channel  130 , which in turn fluidly communicates with liquid transfer section  140 . Thus, water passes through liquid inlet section  120 , into labyrinth channel  130 , and winds through labyrinth channel  130 , ultimately discharging into liquid transfer section  140 . The water exits liquid transfer section  140  via an opening  142  disposed at each end thereof, and subsequently enters generally annular discharge regions  145 , each of which is distally located with respect to labyrinth channel  130 , i.e., towards each emitter end fixture  160 . 
         [0046]      FIG. 2  is a perspective view of drip irrigation emitter  100  of  FIG. 1 , disposed within irrigation pipe  210 . According to methods of the prior art, during the extrusion-based process for producing irrigation pipes such as irrigation pipe  210 , drip emitters such as drip emitter  100  may typically be affixed to the interior surface of the pipe, at substantially fixed intervals (time and distance). Apertures such as apertures  147  are formed through the wall of the irrigation pipe, based on the estimated longitudinal position of each drip emitter within the pipe. More specifically, apertures  147  are formed through the wall of the irrigation pipe, based on the estimated longitudinal position of annular discharge regions  145  of each drip emitter  100  within irrigation pipe  210 . The longitudinal length Lp of each annular discharge region  145  is typically 4-7 mm, to ensure that each aperture  147  is generally aligned with a respective annular discharge region  145 . 
         [0047]    Water flowrate and optional pressure control are effected upstream of annular discharge regions  145 , such that the main function of discharge regions  145  is to enable passage of the water into a discharge aperture in the wall of the pipe or conduit (as shown in  FIG. 2 ). Thus, annular discharge regions  145  may be considered substantially, functionally passive length sections, in that they are disposed towards the end of the water flowpath, downstream of the pressure reduction section, and any pressure control section. The pressure reduction section (e.g., a labyrinth), and pressure control section of the drip emitter may be considered functionally active sections. 
         [0048]    The market for drip irrigation systems is continually demanding improved performance and improved cost efficiencies for these systems. I have recognized several deficiencies in discharge region  145 , including appreciable waste of raw materials, additional energy expenditure per emitter produced, relatively high shipping and storage volumes, and lower throughput of emitters through the feeding system. 
         [0049]    Referring again to  FIG. 1 , the total length L of emitter  100  substantially consists of the sum of the total length of a functionally active section  175  (described in greater detail hereinbelow), the length of each emitter end fixture  160 , and the length of each annular discharge region  145 : 
         [0000]        L=La+ 2 ·Le+ 2 ·Lp.    
         [0050]    Significantly, the length ratio of the annular discharge regions to the total length of the prior art emitters may be at least 0.25, and more typically, at least 0.30. In some of the more advanced, compact emitters of the prior art, the length ratio of the annular discharge regions to the total length of the emitter body may be at least 0.35. 
         [0051]    I have discovered that a method in which Lp may be substantially eliminated, enabling the use of a drip emitter that is at least 25-35% more compact with respect to emitters of the prior art. As will be elaborated in detail hereinbelow, the cylindrical-type drip emitters according to the present invention are designed to effect an at least partial discharge of the effluent water via a region that is longitudinally aligned with a functionally active section of the emitters, thereby obviating the need for the annular discharge regions of the prior art. 
         [0052]    With reference now to  FIG. 3  and  FIG. 4 ,  FIG. 3  is a perspective view of a drip irrigation emitter  300  according to an exemplary embodiment of the present invention.  FIG. 4  is an axially cut-open view of drip irrigation emitter  300  of  FIG. 3 , disposed within irrigation pipe  210 . Drip irrigation emitter  300  is an in-line, cylindrical emitter, adapted to be disposed within, and secured within or attached (e.g., bonded) to, an irrigation pipe  210 , shown in  FIG. 4 . Emitter  300  may include a filtration or liquid inlet section  320 , at least one pressure-reducing section such as a labyrinth channel  330   a , and at least one functionally passive section or liquid transfer section such as section  340   a , a small portion of which can be seen in  FIG. 3 . 
         [0053]    Emitter  300  may advantageously have an emitter end fixture  360  on each longitudinal end of the emitter. Emitter end fixture  360  may be identical or substantially identical to emitter end fixtures known in the art, such as emitter end fixture  160  provided in  FIG. 1 . 
         [0054]      FIG. 4  shows an inner facing  315  of emitter  300 . Inner facing  315  may advantageously include a plurality of inlet openings or apertures such as openings  326 , which provide fluid communication between a volume contained by inner facing  315  and an outer facing  350  of emitter  300 . As will be appreciated by one of ordinary skill in the art, openings  326  are adapted to inhibit coarse particles in the water from entering, and clogging, emitter  300 . 
         [0055]    The vast majority of the water within irrigation pipe  210  flows in longitudinal fashion through emitter  300 , and flows out into downstream section  212  of irrigation pipe  210 . A minute fraction of the water flows through openings  326 , towards outer facing  350  of emitter  300 . Having passed through filtration section  320 , the water is now free to flow into labyrinth channel  330   a . The flow of water exits labyrinth channel  330   a  via labyrinth intermediate channel  332 , which may typically extend to an opposite side or face of emitter  300 , shown in  FIG. 5 . 
         [0056]    Over the course of the tortuous path of labyrinth channel  330   a , a designed, pre-determined, or otherwise pressure drop may be achieved, as will be readily understood by those of ordinary skill in the art. 
         [0057]      FIG. 5  provides another perspective view of drip irrigation emitter  300 , in which labyrinth channel  330   b  and a functionally passive section or liquid transfer section  340   b  are prominently displayed. Labyrinth channel  330   b  fluidly communicates with intermediate channel  332  (shown in  FIG. 3 ), whereby the flow of water is discharged from intermediate channel  332  into a first or proximal end of labyrinth channel  330   b.    
         [0058]    The far or distal end of labyrinth channel  330   b  fluidly communicates with liquid transfer section  340   b . It may be advantageous, as shown in  FIG. 5 , for the distal end of labyrinth channel  330   b  to fluidly communicate directly with a distribution passageway  335 , which in turn feeds into liquid transfer section  340   b , and preferably, into liquid transfer section  340   a  as well. 
         [0059]    Liquid transfer sections  340   a  (shown in  FIG. 3) and 340   b  have a particular radial orientation with respect to the body of emitter  300 . In exemplary emitter  300 , each of liquid transfer sections  340   a  and  340   b  are disposed on an arc or contour representing about 25% of the total outer perimeter or circumference of emitter  300 . It will be appreciated by those of ordinary skill in the art that the number of liquid transfer sections, as well as the individual and total fractions of the emitter perimeter or circumference, may vary due to various design constraints or choices. It is critical, however, that the total fraction of the emitter perimeter or circumference be less than 1, and typically less than 0.8, less than 0.7, or less than 0.6, to enable the disposition of at least one functionally active section (e.g., a pressure reducing section or a pressure controlling section) substantially alongside the liquid transfer section or sections, within the same longitudinal section or segment of the emitter body. This arrangement will be elaborated further with respect to  FIGS. 6 and 7 . 
         [0060]      FIG. 6  is a side view of drip irrigation emitter  300 . The length L of emitter  300  includes the length of a first emitter end fixture  360   a  (length=Le), at least one functionally active section such as section  675  having a total length La along the body of emitter  300 , and the length of a second emitter end fixture  360   b . Emitter end fixtures  360   a ,  360   b  are typically identical, such that the total length of these fixtures is 2·Le. 
         [0061]    Typically, length L of emitter  300  consists of, or substantially consists of, the sum of the total length of functionally active section  675  and the lengths of emitter end fixtures  360   a ,  360   b:    
         [0000]        L=La+ 2 ·Le.    
         [0000]    In this exemplary embodiment, the length La of functionally active section  675  is determined by the sum of the length of liquid inlet section  320  and the length of the labyrinth channel (e.g., labyrinth channel  330   a ). More generally, functionally active section  675  may include a pressure controlling section (an exemplary embodiment of which is provided in  FIG. 9  and the associated description). Also, the sections of labyrinth channel provided herein are meant as exemplary embodiments of pressure reducing sections. It will be appreciated that various types of pressure reducing means and sections will be apparent to those of ordinary skill in the art. 
         [0062]    Referring now to  FIG. 7 ,  FIG. 7  is a perspective view of inventive drip irrigation emitter  300 , disposed within irrigation pipe  210 . In emitter  300 , water or liquid discharged from functionally active section  675  may collect within functionally passive section or liquid transfer section  340   b , or between section  340   b  and an inner surface  712  of pipe  210 . A discharge aperture  747  is disposed in the wall of pipe  210 , such that section  340   b  may fluidly communicate with, or directly fluidly communicate with, an environment outside of pipe  210 , via aperture  747 . 
         [0063]    Discharge aperture  747  is both longitudinally aligned within a longitudinal segment defined by functionally active section  675 , and radially aligned with functionally passive section  340   b . Inadvertent misalignment of discharge aperture  747 , whereby aperture  747  is radially aligned with a functionally active section, may severely compromise or destroy the function of the emitter. 
         [0064]    Referring back to  FIG. 6 , obviation of the annular discharge regions of the prior art cylindrical emitters enables an increased ratio of the total length La of the functionally active sections to length L of the emitter body. This length ratio may be at least 0.60, or at least 0.65, and more typically, at least 0.70, at least 0.75, at least 0.78, at least 0.80, at least 0.82, or at least 0.85. 
         [0065]      FIG. 8  is a perspective view of another exemplary embodiment of a drip irrigation emitter  800  according to the present invention, disposed within a pipe  810 . As with drip irrigation emitter  300  provided in  FIG. 7 , water or liquid discharged from the functionally active section of the emitter may collect within functionally passive section or liquid transfer section  340   b , or between section  340   b  and an inner surface  812  of pipe  810 . A discharge aperture  747  is disposed in the wall of pipe  210 , such that section  340   b  may fluidly communicate with, or directly fluidly communicate with, an environment outside of pipe  810 , via aperture  747 . Discharge aperture  747  is both longitudinally aligned within a longitudinal segment defined by functionally active section  675 , and radially aligned with functionally passive section  340   b.    
         [0066]    Drip irrigation emitter  800  has a generally annular discharge region  845 , which may be substantially similar to annular discharge region  145  described with respect to  FIG. 1 . Annular discharge region  845  is disposed between functionally active section  675  and emitter end fixture  160 . An additional aperture  847  is formed through the wall of pipe  810 , based on the estimated longitudinal position of annular discharge region  845  of each drip emitter  800  within irrigation pipe  810 . 
         [0067]      FIG. 9  provides a perspective view of a pressure-controlling drip irrigation emitter  900 , according to another exemplary embodiment of the present invention. As described hereinabove, the pressure-controlling section forms a portion of the functionally active section of the emitter. The pressure-controlling section is not described in detail, being well known to those of ordinary skill in the art of irrigation drip emitters. 
         [0068]      FIG. 10  is a perspective view of another embodiment of a drip irrigation emitter  1000 , according to the present invention. In this exemplary embodiment, an outer surface  1105  of emitter  1000  has an arc or contour (a) of about 160°. The outer surface of the drip emitters of the present invention typically span at least 140°, at least 160°, or at least 180°. 
         [0069]      FIG. 11A  is a perspective view of a drip emitter  1100  according to another exemplary embodiment of the present invention, disposed within a non-cylindrical irrigation pipe  1110  having a non-cylindrical contour. 
         [0070]      FIG. 11B  is a wire-rim drawing of drip irrigation emitter  1100 . In this exemplary embodiment, an outer surface  1105  of the emitter body has a contour (a) of about 250°. 
         [0071]      FIG. 12A  is a generally axial view of a drip emitter  1200  according to another exemplary embodiment of the present invention, having alignment protrusions  1292 ,  1294  and  1296  disposed in an outer facing  1205  of emitter  1200 . Alignment protrusion  1296  may be disposed on a radially opposite side of emitter  1200 , with respect to alignment protrusions  1292 ,  1294 . 
         [0072]      FIG. 12B  is a perspective view of drip emitter  1200 , disposed within a pipe  1210 . Typically, drip emitters such as drip emitter  1200  are inserted into an irrigation pipe such as pipe  1210 , after the pipe has been extruded. Alignment protrusions  1292 ,  1294  may be adapted whereby, during the insertion of drip emitter  1200  into pipe  1210 , external protrusions are formed in an outer surface  1212  of pipe  1210 . Consequently, the radial alignment of emitter  1200  within pipe  1210  may be observed or determined based on the radial positioning of these external protrusions. 
         [0073]    Knowing the radial alignment of emitter  1200  within pipe  1210  may be important in identifying the proper position of discharge apertures such as discharge aperture  747  (shown in  FIGS. 7 and 8 ). 
         [0074]    Alternatively or additionally, an external mark (stripe, groove, etc.) may be made on outer surface  1212  of pipe  1210 , to designate the radial alignment of emitter  1200  within pipe  1210 . 
         [0075]    Various detection means, including electromagnetic detection methods and apparatus, may be utilized to determine a position of the drip emitter within the pipe. Such methods and apparatus may include, but are not limited to, X-ray imaging or infra-red imaging. 
         [0076]    As used herein in the specification and in the claims section that follows, the term “functionally passive section”, with respect to an emitter or emitter body, refers to a section disposed towards a downstream end of the water flowpath, i.e., downstream of the pressure reduction section, and any pressure control section. 
         [0077]    As used herein in the specification and in the claims section that follows, the term “functionally active section”, with respect to an emitter or emitter body, is meant to include a section in which the pressure is controlled and/or reduced. The term “functionally active section” is further meant to include a liquid inlet section such as filtration or liquid inlet section  320  shown in  FIG. 3 . 
         [0078]    As used herein in the specification and in the claims section that follows, the term “pressure-reducing section”, with respect to a drip emitter, is meant as used by those of skill in the art of drip irrigation emitters. One typical type of pressure-reducing section is a labyrinth-containing section. 
         [0079]    It will be appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. 
         [0080]    Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.