Abstract:
A liquid atomizer for agricultural use includes at least one canal in fluid communication via a chamber with an outlet. At least a section of the canal extends along a straight line and tangentially opens into the chamber.

Description:
BACKGROUND 
       [0001]    The present disclosure relates to liquid atomizers for use in agriculture. 
         [0002]    Such liquid atomizers, which may also be referred to as foggers, sprayers, mist devices, humidifiers, etc., emit a fine mist of liquid. This fine mist may be achieved by guiding a liquid jet through a vortex path that causes the jet to swirl and exit the atomizer as a spray. These atomizers may be used for conditioning the environment by increasing humidity such as in a greenhouse. 
         [0003]    U.S. Pat. No. 6,983,896, the disclosure of which is incorporated herein by reference, describes an atomizer with a vortex generating member that is fitted with an R-like vortex generating paths. Water flowing through the atomizer is forced to spin in the R-like path and exit as a fine spray of atomized liquid via a narrow outlet after it is swirled. 
         [0004]      FIGS. 8 to 10  show a prior art atomizer  100  having a housing  110  with a vortex or swirl chamber  120 . Water flowing though the atomizer  100  is directed along a curved canal  130  into a cylindrical section of the chamber  120  and then along a coned section of the chamber  120  until exiting the atomizer  100  as mist. 
       SUMMARY 
       [0005]    The following embodiment 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. 
         [0006]    In an embodiment, a liquid atomizer comprises at least one canal, a swirl chamber and an outlet that are formed therein, the canal being in fluid communication via the chamber with the outlet and the outlet opening out of the atomizer, wherein at least a section of the canal extends along a straight line and tangentially opens into the chamber to thereby form tangential direction and velocity to liquid jets entering the chamber. 
         [0007]    In some embodiments, the chamber comprises a cylindrical portion into which the section of the canal opens and a coned portion, the cylindrical portion extending down towards the coned portion and the coned portion tapering down towards the outlet. Opening out of the canal sections into the cylindrical portion assists forming the liquid jets exiting the canals into a uniform flow. 
         [0008]    In some embodiments, the canal has a canal face and an imaginary line included in the canal face and parallel to the straight line tangentially meets a periphery of the cylindrical portion. 
         [0009]    In some embodiments, the section of the canal is a closed canal. This closed section may be formed by a part of the atomizer that abuts the open canals to form a ceiling or by forming a closed canal that passes through a portion of the atomizer. In the event that the canals are closed by a ceiling it is preferable that the part forming the ceiling is made of non-metal material with sealing properties. 
         [0010]    In some embodiments, the coned portion of the chamber has a cone head angle α greater than or equal to 60 degrees and smaller than or equal to 135 degrees. Other angle values may, inter alia, impair optimal tangential velocity in the swirl chamber and decrease the spray angle exiting the outlet. 
         [0011]    In addition to the exemplary aspects and embodiment 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 
         [0012]    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 disclosure, 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: 
           [0013]      FIG. 1  shows a perspective bottom view of a liquid atomizer in accordance with the present disclosure; 
           [0014]      FIG. 2  shows an exploded view of the atomizer; 
           [0015]      FIG. 3  shows a partial cross sectional view of the atomizer taken in the plane A-A in  FIG. 1 ; 
           [0016]      FIG. 4  shows a partial cross sectional view of a housing of the atomizer taken in the plane A-A in  FIG. 1 ; 
           [0017]      FIG. 5  shows a top view of the housing of the atomizer; 
           [0018]      FIG. 6  shows a partial cross sectional view of the housing taken along the line VI-VI in  FIG. 5 ; 
           [0019]      FIG. 7  shows a perspective view of an atomizer head incorporating atomizers in accordance with the present disclosure; 
           [0020]      FIG. 8  shows a perspective bottom view of a prior art atomizer; 
           [0021]      FIG. 9  shows a longitudinal cross sectional view of the prior art atomizer; and 
           [0022]      FIG. 10  shows an enlarged top view of a housing of the prior art atomizer. 
       
    
    
       [0023]    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 
       [0024]    Attention is first drawn to  FIGS. 1 and 2  showing a pressure liquid atomizer  10  having an adaptor  12 , a bushing  14  and a housing  16 . Liquid from a liquid source (not shown), at a typical inlet pressure of between  3  to  5  bars, flows into the atomizer  10  via the adaptor  12  and is emitted from the atomizer  10  as a spray via an outlet  50  of the housing  16 . The atomizer  10  is preferably formed from materials that are resistant to damage caused by plant nutrients and other materials that may be used in agriculture. Optionally, at least some of the parts of the atomizer are formed from Polybutylene terephthalate (PBT). 
         [0025]    The atomizer  10  has a longitudinal axis X defining opposing top and bottom directions therealong. It should be noted that directional terms appearing throughout the specification and claims, e.g. “top”, “bottom”, etc., (and derivatives thereof) are for illustrative purposes only, and are not intended to limit the scope of the appended claims. In addition it is noted that the directional terms “bottom”, “down”, “below” and “lower” (and derivatives thereof) define identical directions and the directional terms “top”, “up”, “above” (and derivatives thereof) define identical directions. 
         [0026]    Attention is additionally drawn to  FIGS. 3 and 4 . The adaptor  12  has an axially extending lumen  18  that opens out to top and bottom ends thereof and a gasket  20  of the adaptor  12  surrounds a bottom portion thereof. The bushing  14  has a lower cylindrical shank  22 , an upper cylindrical rod  24  and an annular ring  26  therebetween. The shank  22  has a downwardly facing base  28  at a lower end thereof and the ring  26  has an upwardly facing annular support  30 . A base edge  32  is defined at the intersection of the base  28  with a periphery of the shank  22 . 
         [0027]    An axially extending main channel  34  and two minor channels  36  are formed in the bushing  14 . The main channel  34  is closed at a bottom end and opens out to an upper end of the bushing  14 . The minor channels  36  communicate with the main channel  34  and extend laterally to open out at opposing sides of the periphery of the shank  22 . 
         [0028]    The housing  16  has an axially extending cavity  38  having an upper portion  40 , a lower portion  44  and a middle portion  42  therebetween. The upper and middle portions  40 ,  42  are cylindrical and coaxial and the middle portion  42  has a smaller diameter than the upper portion  40 . The lower portion  44  (best seen in  FIG. 4 ) has an inlet  46 , an outlet  50  and a swirl chamber  48  therebetween. The inlet  46  has an upwardly facing floor  52  at a lower end thereof and a peripheral wall  54 . The inlet  46  extends down from the cavity&#39;s middle portion  42  to the floor  52 . 
         [0029]    Attention is additionally drawn to  FIGS. 5 and 6 . Two bulges  56  of the housing  16 , symmetrically distributed about the axis X, project into the inlet  46 . A keyway  58  of the inlet  46  is defined as a portion of the inlet  46  located annularly between adjacent bulges  56 . A portion of the wall  54  facing into the inlet  46  and located on each bulge  56  lies on a segment of a cylinder having an axis coinciding with X and a diameter Db. A portion of the wall  54  bounding each keyway  58  and facing into the inlet  46  lies on a segment of a cylinder having an axis coinciding with X and a diameter Dk which is larger than Db. 
         [0030]    The swirl chamber  48  opens out to the inlet  46  at the floor  52  and has an upper peripheral barrel face  60  and a lower peripheral cone face  62  (best seen in  FIG. 4 ). The barrel face  60  extends a distance H axially down from the floor  52  of the inlet  46  and the cone face  62  tapers down from the barrel face  60  to the outlet  50  at a cone head angle α. The outlet  50  communicates with the swirl chamber  48  and has an axially extending cylindrical shape that extends downwardly therefrom and opens out of the housing  16 . The outlet  50  has a length Lo along the axis and a diameter Do. 
         [0031]    The housing  16  has two canals  64  symmetrically distributed about the axis X that are formed therein (best seen in  FIG. 5 ). Each canal  64  extends along a straight canal axis C and has a canal face  66 . The canal face  66  has opposing sides  68  equally spaced from the canal axis C and an upwardly facing ground  70  that extends between the sides  68 . The canal  64  opens out to the inlet  46  at the floor  52 . In contrast to the curved canal  130  which opens to the swirl chamber  120  of the prior art atomizer  100 , a straight portion of the canal  64  tangentially opens out to the swirl chamber  48  at a merge  72  located on the barrel face  60 . A width b of the canal  64  is measured between the sides  68  and a height h of the canal  64  is measured between the ground  70  of the canal  64  and the floor  52  of the inlet  46 . In a plane perpendicular to the axis X and including the canal axes C, a swirl radius R of the atomizer  10  is defined as the distance between a given canal axis C and an imaginary line L R  parallel to the canal axis C and intersecting the axis X. Preferably, an imaginary line L T  parallel to the canal axis C and lying on the canal face  66  is tangential to the barrel face  60  at the merge  72 . It is noted that embodiments of an atomizer  10  in accordance with the present disclosure may have one canal  64  or more than two canals  64  and respectively one or more than two key ways  58  and minor channels  36 . 
         [0032]    Attention is drawn back to  FIG. 3 . In an assembled state of the atomizer  10  the bushing  14  is first attached to the adaptor  12  by urging the rod  24  of the bushing  14  into the lumen  18  of the adaptor  12  until a bottom end of the adaptor  12  abuts the support  30  of the bushing  14 . The adaptor  12  and bushing  14  are then urged into the cavity  38  of the housing  16  with the bushing  14  leading until the bushing&#39;s shank  22  is snugly received between the bulges  56  and the bushing&#39;s base  28  abuts the inlet&#39;s floor  52 . It will be understood from hereon that any reference to the atomizer  10  refers to the atomizer  10  in its assembled state. 
         [0033]    Attention is additionally drawn to  FIG. 5  with a note that the base edge  32  is marked in this figure with a dashed line. The base  28  of the bushing  14  in the atomizer  10  covers sections the canals  64  to form closed canal sections  74  having a length y measured along the canal axis C between the base edge  32  and the merge  72 . During operation of the atomizer  10 , liquid flows downwardly through the lumen  18  into the main channel  34  of the bushing  14  and from there diverges sideways via the minor channels  36  into the middle portion  42  of the cavity  38  below the gasket  20 . The liquid then flows down via the keyways  58  into the canals  64  and then via the closed canal sections  74  tangentially into the swirl chamber  48  wherein it swirls along the barrel and cone faces  60 ,  62  until exiting the atomizer  10  via the outlet  50  as a spray. It is noted that the opening of the closed canals  74  into the barrel face of the swirl chamber helps shape the jets exiting the closed canals  74  into a uniform flow before the exiting via the outlet. 
         [0034]    The inventor performed studies of the efficiency of an atomizer  10  in accordance with the present disclosure. The studies indicate that when at least some of the parameters h, b, R, y, H, Lo and Do comply with the following relationships, an atomizer  10  in accordance with the present disclosure emits a fine liquid spray. Optionally, under liquid pressure of about 0.4 MPa an embodiment of the atomizer  10  emits a spray with liquid particles having a Sauter Mean Diameter (SMD) optionally smaller than 80 μm and preferably smaller than 60 μm. It is noted that some of the following relations are dependant upon each other. 
         [0035]    For optimal tangential velocity in the swirl chamber  48 , the angle α is optionally within the range of 60°&lt;α&lt;135° and the relative length of the outlet  50  is optionally within the range of 
         [0000]    
       
         
           
             0.25 
             ≤ 
             
               
                 L 
                 0 
               
               
                 D 
                 0 
               
             
             ≤ 
             1. 
           
         
       
     
         [0000]    The relative length of the closed canal sections  74  is optionally 
         [0000]    
       
         
           
             
               y 
               b 
             
             ≥ 
             1.5 
           
         
       
     
         [0000]    for the liquid entering the swirl chamber  48  to acquire optimal tangential direction and velocity. The relation between the width and height of each closed canal section  74  is optionally 
         [0000]    
       
         
           
             0.8 
             ≤ 
             
               b 
               h 
             
             ≤ 
             1.3 
           
         
       
     
         [0000]    to provide an optimal inlet area into the swirl chamber  48 . The relation between the total inlet areas into the swirl chamber  48  and the total outlet area out of the swirl chamber  48  is optionally 
         [0000]    
       
         
           
             0.9 
             ≤ 
             
               Nbh 
               
                 π 
                  
                 
                     
                 
                  
                 
                   r 
                   2 
                 
               
             
             ≤ 
             1.9 
           
         
       
     
         [0000]    (wherein N is the number of canals and r=Do/2). The relation between the heights of the swirl chamber&#39;s barrel face  60  and the canals  64  is optionally 
         [0000]    
       
         
           
             1.2 
             ≤ 
             
               H 
               h 
             
             ≤ 
             
               1.8 
               . 
             
           
         
       
     
         [0000]    And finally, to minimize hydraulic losses in the swirl chamber  48  the following relation should optionally be obtained 
         [0000]    
       
         
           
             2.9 
             ≤ 
             
               
                 π 
                  
                 
                     
                 
                  
                 Rr 
               
               Nbh 
             
             ≤ 
             5 
           
         
       
     
         [0000]    (wherein N is the number of canals and r=Do/2). 
         [0036]    By way of a numerical example, an atomizer  10  in accordance with an embodiment of the present disclosure with two canals has the following dimensions. h=0.4 mm, b=0.4 mm, R=1.7 mm, y=0.96 mm, H=0.6 mm, Lo=0.5 mm and Do=0.53 mm. 
         [0037]    Attention is drawn to  FIG. 7 . An atomizer head  77  in accordance with an embodiment of the present disclosure comprises four atomizers  10  that emit each a liquid spray. In addition it is noted that an atomizer head  77  in accordance with an embodiment of the present disclosure can comprise a configuration of a plurality of atomizers  10 , such as a “T” or a “star” configuration. 
         [0038]    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. 
         [0039]    Although the present embodiment has 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 disclosure as hereinafter claimed.