Patent Publication Number: US-6983896-B2

Title: Liquid atomizer

Description:
RELATED APPLICATIONS 
   This is a continuation of parent application Ser. No. 09/722,388, filed Nov. 28, 2000, now U.S. Pat. No. 6,637,673. 

   FIELD OF THE INVENTION 
   The present invention is generally in the field of liquid atomizers and in particular it is concerned with atomizers for agricultural and domestic use. 
   The term “atomizer” as used herein in the specification and claims refers collectively to a device capable of emitting a fine mist of liquid. Such devices are often referred to in the art also as foggers, sprayers, mist devices, humidifiers, etc. 
   BACKGROUND OF THE INVENTION 
   Atomizers used in agriculture and for domestic purposes serve for conditioning the environment both by increasing humidity such as in greenhouses and tropical gardens, for irrigation and for cooling. A variety of atomizers are known, referred to as rotary-cup atomizers, air blast/air assist etc. The present invention is concerned with pressure atomizers. 
   Cooling by atomized liquid is obtained by forcing a liquid, typically water, through specially designed nozzles so as to obtain a fog of ultra fine water droplets. The liquid droplets absorb heat energy of the environment and evaporate, whereby the energy (heat) consumed for converting the liquid into gas (vapor) is extracted from the environment, thus cooling the air. 
   The amount of moisture in the air divided by the maximum amount of moisture there could be absorbed at the same temperature (relative humidity) is a significant parameter in determining cooling potential. The lower the relative humidity, the more liquid can be vaporized, thus the more heat can be removed from the environment. Evaporative cooling can be used in most geographical zones owing to the fact that when temperature reaches its peak during day, relative humidity is normally at its lowest. For this reason, evaporative cooling is commonly used in many zones over the world. 
   Liquid atomizers are at times, used also as frost protectors by creating a mist layer above the agricultural growth, thus preventing frost from damaging the crops. 
   Pressure atomizers are commonly in use and typically comprise a housing fitted with at least one outlet nozzle, a core member associated with each nozzle for generating a vortex (often referred to in the art as “swirl”) and a strainer/washer member packed together by screw coupling of the nozzle to the housing. The atomized spray is obtained by guiding a liquid jet through a path causing the jet to swirl and upon exiting through a fine outlet nozzle, an atomized spray is emitted. 
   Typically, each outlet nozzle is associated with a single housing and where covering a large area with mist is required, thus several such housing may be mounted on a splitting element, each such outlet nozzle being directed to a different direction and said splitting element being connected in turn to a liquid supply line. 
   It is an object of the present invention to provide a novel and improved liquid atomizer. The number of components, by one of its preferred embodiments, being reduced as compared with prior art such devices. 
   SUMMARY OF THE INVENTION 
   The present invention provides a liquid atomizer for use in agriculture and for domestic use and is aimed, by one of its preferred embodiments, at providing an atomizer comprising a reduced number of components. The liquid atomizer comprises a housing fitted with an inlet for connecting to a liquid supply line and a cavity being in flow communication with the inlet, said cavity having a longitudinal axis; a peripheral member formed with at least one outlet nozzle for emitting atomized liquid; and a vortex generating member formed with a vortex generating path being in flow communication with the cavity and extending opposite a respective outlet nozzle; each vortex generating path generates a liquid vortex about an axis transversally extending relative to the longitudinal axis of the housing. 
   According to one embodiment, the peripheral member is integral with the housing and the vortex generating member is sealingly received within the cavity of the housing. According to another embodiment, the vortex generating member is integral with the housing and the peripheral member is mounted over the vortex generating member. 
   In accordance with another embodiment, the vortex generating member is coaxial with the housing and is sealingly received therewithin. By one embodiment it is radially fixable within the housing. 
   Typically one or more outlet nozzles are circular. However, they may also be or otherwise shaped nozzles so as to distribute a selected fog pattern. 
   By one preferred arrangement, the housing and the vortex generating member are cylindrical, wherein the vortex generating member is snapingly fixed to the housing and may be displaced into other functional positions. In accordance with a preferred design of this arrangement, peripheral walls of the vortex generating member sealingly bear against inner walls of the housing, thus preventing liquid flow between the walls of the vortex generating member and the housing. However, a sealing member may be introduced between the vortex generating member and the housing. 
   In accordance with one specific and preferred embodiment, the vortex generating path generates a liquid vortex about an axis substantially perpendicular to the longitudinal axis of the housing. 
   In accordance with one arrangement of the invention, the vortex generating path has an inlet extending parallel to the longitudinal axis and originating at an edge of the vortex generating member. In accordance with another construction, the vortex generating member has a bore being in flow communication with the cavity and the vortex generating path has an outlet originating from the bore. This arrangement is in particular suitable for including a sealing member between the vortex generating member and the housing. 
   In accordance with one arrangement, the vortex generating path has an R or P like cross-section with the center of the round portion extending opposite the respective outlet nozzle and wherein the respective leg portions of the R and P like shapes constitute the opening of the path. In accordance with a second arrangement, the vortex generating path has a cochlea-like (spiral) cross-section with the center thereof extending opposite the respective outlet nozzle. 
   According to a variation of the above embodiments, the vortex generating path is formed with two (or more) leg portions for increasing the flow rate, the leg portions extending from an edge of the vortex generating member which is in flow communication with the cavity, or have at least one leg being in flow communication with the cavity via a hollow formed in the vortex generating member which is in flow communication with the cavity. 
   In accordance with another variation of the invention, the vortex generating member comprises a plurality of vortex generating paths and the housing comprises a plurality of outlet nozzles; the vortex generating paths and the outlet nozzles being distributed at different angular divisions; the vortex generating member is fixable within the housing at different radial positions, each giving rise to cooperation of different outlet nozzles with respective vortex generating paths and to sealing-of other outlet nozzles. This arrangement enables to determine the number of active nozzles within a single housing, allowing to increase or decrease the number of active nozzles so as to obtain different sectorial coverage of mist. 
   By another design, some of the vortex generating paths of the vortex generating member are axially offset and some of the outlet nozzles of the housing are offset in a corresponding manner, whereby axial or angular displacement of the vortex generating member with respect to the housing entails engagement of a different vortex path with a different outlet nozzle. In this way it is possible to select different fog patterns, outlet rate, etc. By a modification thereof, at least one outlet nozzle and at least one vortex generating member are axially offset. 
   The housing and vortex generating member are fitted with corresponding mating members for setting the vortex generating member at the different radial positions within the housing. 
   The arrangement of the liquid atomizer in accordance with the present invention reduces to minimum the number of components wherein each housing is fitted with a single vortex generating member whereby a single housing is required for several outlet nozzles. 
   By a different application of the invention, the inlet is in flow communication with a pressure threshold valve received before or after the inlet. By a preferred embodiment, the pressure threshold valve is received within the cavity of the liquid atomizer. In accordance with one such design, the pressure threshold valve comprises a closure member biased against the inlet of the housing. 
   In accordance with another embodiment, the pressure threshold valve is a leakage preventing device (LPD), wherein the closure member is spring biased against the inlet of the housing and has a piston rod connecting it with a piston, said piston being displaceable along a corresponding cylinder, which is in flow communication with the cavity. The LPD arrangement provides for opening of the closure member at a predetermined pressure threshold wherein the inlet is rapidly opened into a maximal open stage. This may be obtained by a structure in which the piston is sealingly displaceable within the cylinder and wherein liquid entering the cavity applies force on the piston in a direction entailing displacement of the closure member away from the inlet. 
   In accordance with such an embodiment, it is desired that the cylinder is vented to the atmosphere. In accordance with a modification of the invention, the piston is displaceable against a membrane fitted at an end of the cylinder. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For better understanding, the invention will now be described, in a non-limiting example only, by way of example only, with reference to some accompanying drawings, in which: 
       FIG. 1A  is an exploded isometric view illustrating the atomizer of the present invention, with replacement fog generating members; 
       FIGS. 1B to 1E  illustrate different embodiments of vortex generating members; 
       FIG. 2  is a longitudinal sectional view of an atomizer in accordance with the present invention fitted with a leakage preventing device; 
       FIG. 3  is a longitudinal sectional view of an atomizer in accordance with the invention integrally fitted with a leakage preventing device; 
       FIG. 4  is a different embodiment of a liquid atomizer in accordance with the invention fitted with still a different leaking preventing device; 
       FIG. 5  is a longitudinal section of an atomizer in accordance with the present invention integrally fitted with a pressure threshold valve; 
       FIG. 6  is a perspective view of a sector-adjustable atomizer in accordance with the present invention; 
       FIGS. 7A–7D  are sectional views along line VII—VII in  FIG. 6  referring to four consecutive positions suitable for emitting an atomized spray at four different sectorial positions; 
       FIG. 8  is a perspective exploded view of an atomize according to still an embodiment of the invention; 
       FIGS. 9A–9C  are perspective views illustrating three different operative positions of the atomizer of  FIG. 8 ; 
       FIG. 10  is an isometric, exploded view of a further embodiment of an atomizer in accordance with the present invention; 
       FIG. 11  is a cross-sectional view of the atomizer of  FIG. 10 , assembled; 
       FIG. 12  is an exploded view of an atomizer according to another embodiment of the invention; and 
       FIG. 13  is a longitudinal section of the atomizer of  FIG. 12 , in an assembled state. 
   

   DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS 
   Attention is first directed to  FIG. 1  of the drawings illustrating an atomizer generally designated  20  consisting of two principle components, namely a housing  22  and a vortex generating member  24 . Housing  22  is cylindrical and comprises a cylindrical cavity  26  being in flow communication with an inlet  28  which may be attached by known means (press fit, screw threading, etc.) to a water supply line (not shown). It is clear that a cylindrical housing is only an example and any other shape is possible too. 
   Radially extending from the cavity  26  there are four outlet nozzles  32  (only three seen) extending from the cavity  26  to an external surface of the housing  22 . As can further be seen in  FIG. 1A , the housing is fitted adjacent an upper edge thereof with an annular groove  38  for snapping and sealingly receiving a corresponding annular rim  40  formed at the vortex generating member  24 . If required, a suitable O-ring may be provided within a suitable groove. 
   The vortex generating member  24  is a plug-like member having a cylindric portion  44  adapted for tight and sealing engagement within the walls  46  of cavity  26  of the housing  22  essentially not leaving an interstice between the mating surfaces whereby liquid cannot flow between wall  46  and the cylindric portion  44  of the vortex generating member  24 . 
   Vortex generating member  24  is fitted, in the present example, with four vortex generating paths  50  (two seen in  FIG. 1A ) each having an R-like cross-section with an inlet portion  52  extending between the legs of the R-like shape at an edge  56  of the cylindric portion  44  with the center of the R-like portion  58  extending essentially opposite an opening of a corresponding nozzle  32  formed in the housing  22 . 
   In the assembled position, which can be seen in cross-section in  FIG. 2 , water enters the cavity  26  through the inlets  28  and is then forced to flow into the vortex generating paths  50  extending between the wall  46  of the cavity  26  and the path  50 , whereby the water enters through the widened inlet portion  52 , forced to spin within the R-like or R-shaped portion  58  and exits through the narrow outlet  32  after it is swirled, so as to emit a fine spray of atomized liquid. 
   It is noticed that the housing  22  is formed around the outlet nozzles  32  with a reflector-like indentation  60  in order not to interfere with the atomized water. 
   It will further be appreciated that the vortex generating member  24  is sealingly received within the housing  22  in a tight manner and in a manner in which it is angularly fixed therewithin, to ensure that the vortex generated at the round portion  58  of vortex generating portion  50  is axially aligned with the outlet nozzle  32  of the housing  22 . This may be, for example, by providing suitable projections and corresponding receiving recesses. 
   In  FIG. 1B , there is illustrated a vortex generating member  61  which is similar to vortex generating member  24  in  FIG. 1A , the different residing in the vortex generating path  62  which has an opening portion  63  similar to opening portion  52  and terminates at a cochlea-like pattern  64 , ending opposite an outlet nozzle when assembled within a housing of the atomizer. 
     FIG. 1C  is still a different embodiment of a vortex generating member  65 , having a P-like vortex generating path  66  formed with a bore  67  extending from a hollow of the vortex generating member (which is in flow communication with the cavity of the housing). The path  66  has a round vortex generating portion  68  as explained in connection with  FIG. 1A . The arrangement in accordance with the embodiment of  FIG. 1C  is that a suitable sealing member, e.g. an O-ring  69 , may be provided between the housing and the vortex generating member for improved sealing therebetween. 
     FIGS. 1D and 1E  illustrate modifications of the vortex generating member. In  FIG. 1D  the vortex generating member  70  is formed with vortex generating paths  72  having two inlet ducts  73  and  74  both extending from a bottom edge of the member  70  into a circular shaped well  75 . This arrangement is useful for increasing flow rate. 
   The vortex generating member  76  ( FIG. 1E ) has a circular well portion  77  into which extend one inlet duct  78  extending from a bottom edge (as in  FIG. 1D ) and a second inlet duct  79  formed with a bore  80  (as in  FIG. 1C ). 
   As can further be noticed in the embodiment of  FIG. 2 , an inlet portion  83  of the housing  22  has venting openings  84  and is screw-fitted with a leakage preventing device (LPD)  81  of a known type, available on the market. The purpose of such an LPD device is to prevent leakage of water from the atomizer by ensuring that water flow into the device is enabled only upon a minimal pressure at the liquid supply line. However, as long as the pressure remains below the predetermined pressure, the LPD device remains closed blocking water flow into the atomizer. Still another feature of the LPD is that once it opens to permit flow into the atomizer, it is fully opened, namely it rapidly displaces between its open and closed position. 
   In the embodiment of  FIG. 3 , the liquid atomizer  86  is substantially similar to the previous embodiments with the exception that it comprises an integral LPD  88 . The housing  90  is fitted with two side flaps  91  to facilitate fit connection with a fluid supply line (not shown). The inlet  92  into the cavity  93  has an upwardly projecting rim  94  for sealing engagement with a closure member, as will become apparent hereinafter. 
   The vortex generating member  96  comprises an annular wall  98  coaxial and parallel with cylindric wall  100 , forming a cylinder  104  vented by means of venting aperture  106 . A closure plate  200  is formed with a sealing portion  202  opposite the rim  94  of inlet  92  and is typically made of a resilient material for improved sealing thereof. Extending from an opposite face thereof there is a piston rod  206  fitted at its opposite end with a piston  210  sealingly displaceable within cylinder  104  by means of O-ring  212 . The closure plate  200  is normally biased into sealing engagement of inlet  88  by means of a coiled spring  216  bearing at one end against closure plate  200  and at an opposed end against a wall of the vortex generating member  96 . 
   The arrangement in accordance with the embodiment of  FIG. 3  is such that as long as the water pressure within the supply line (not shown) does not exceed a minimal predetermined pressure, then the closure plate  200  remains in its closed position, namely, sealing inlet  92 . However, as the water pressure within the supply line exceeds the predetermined pressure threshold to a pressure exceeding the biasing force of the spring  216 , the closure plate  200  displaces away from the rim  94  thereby opening inlet  92 , whereby water entering the cavity  220  enters into the cylinder  104  applying additional force on a bottom surface  222  of piston  210  assisting the displacement of the closure plate  200  from the inlet. Disengagement from the rim  94 , i.e. opening of the inlet  92 , is rapid since the piston  210  is exposed to atmospheric pressure via aperture  106 . When, however, the liquid pressure drops below the predetermined pressure threshold the closure plate  200  sealingly engages the rim  94  of inlet  92  preventing further flow of water into a cavity  220 . 
   In  FIG. 4 , there is illustrated still another embodiment of a liquid atomizer  230  differing from the previous embodiments mainly in the design of the leaking preventing device. Housing  232 , in the present example is fitted with an external threading for connecting to a liquid supply line (not shown) and is formed with an inlet  234  extending into a cavity  236 . The vortex generating member  238  is formed with a shoulder  240 . In the assembled position there is a flexible closure member  242  sealingly bearing against the inlet  234  and being pliable, upon pressure rise of fluid at the inlet side thereof, to disengage from the inlet  234  allowing liquid to flow into the cavity  236  whereupon liquid pressure is applied on an increased area of the closure member  242  assisting its further deformation into disengagement from the inlet  234 . However, upon pressure drop of the fluid ingressing the cavity  236 , the closure member  242  reverts to its original position in which it sealingly bears against the inlet  234 . A space  243  at an opposite side of the closure member  242  is vented by means of opening  244  to allow fast deformation of the closure member. 
   In this embodiment there is provided an O-ring  239  sealing between the housing  232  and the vortex generating member  238 . 
   According to a modification of the embodiment of  FIG. 4 , there is provided a spring (not shown) for biasing the closure member  242 , at a predetermined force, towards the inlet opening of inlet  234 . 
   The embodiment of  FIG. 5  resembles in a way the embodiment of  FIG. 3 . However, a space  260  is sealed by a flexible diaphragm  262  preventing ingress of water into the confined space  260  whereby a pressure threshold valve is obtained, namely the closure member  264  remains in a sealing position against inlet  266  as long as the liquid inlet pressure does not reach a minimal predetermined threshold level and then only it begins to displace away from the inlet in correlation with the pressure change, namely, at a low pressure threshold the closure member  264  will only slightly displace whereas at the more significant pressure threshold the closure member will displace accordingly. 
     FIGS. 6 and 7  are concerned with an embodiment of the invention wherein the housing  280  is similar to the housing in accordance with the previous embodiments and comprises four outlet nozzles  282 A– 282 D (only two seen in  FIG. 6 ) and a visible position indicator  284 . The vortex generating member  288  is formed with ten vortex generating paths indexed  290 A– 290 J ( FIG. 7 ) being angularly shifted from one another in a manner which at different angular settings of the vortex generating member  288  with respect to the housing  280  an atomized spray is emitted through either one, two, three or four respective outlet nozzles of the housing, as desired. This may be obtained by rotating the vortex generating member  288  within the housing  280  such that at each time one or more of the vortex generating paths face one or more corresponding outlet nozzles of the housing. 
   In accordance with this embodiment the liquid atomizer may be useful for emitting the atomized spray at a variety of sectors as may be required at different settings within a hothouse, etc. 
   It will be, however, appreciated that whilst in accordance with one embodiment the vortex generating member  288  is rotatable within the housing  280 , in accordance with another embodiment it may be fixed within the housing and the arrangement of a plurality of vortex generating paths as illustrated in  FIGS. 7A–7D  is factory set. A further embodiment may of course be such that there exist an additional position in which all the outlet nozzles are blocked, namely, no atomized jet is emitted. 
     FIGS. 8 and 9  illustrate still another embodiment in which the atomizer  300  is capable of distributing the atomized liquid at different sectors, varying outflows and at different patterns. The atomizer  300  comprises a housing  302  and a mating vortex generating member  304 . 
   Housing  302  is principally similar to previous embodiments with the exception that it comprises a plurality of outlet nozzles:  306  having a respective large diameter;  308  having a smaller diameter; and  310  having an elongate shape. It is noted that the outlet nozzles are angularly shifted and furthermore that outlet nozzles  306  and  310  are formed at essentially the same level, wherein outlet nozzle  308  is formed at a lower level. 
   Vortex generating member  304  is formed, in the present example, with two vortex generating paths  314  and  316  axially extending above one another, where the former is in flow communication with the cavity via openings  318  and the later is in flow communication with the cavity via ducts  320  and  321 , as explained hereinabove with reference to  FIGS. 1C–1E . 
   The arrangement is such that at an initial position ( FIG. 9A ) outlet nozzle  306  extends opposite vortex generating path  314 , whilst outlet nozzles  308  and  310  are inoperable, namely do not extend opposite a corresponding vortex generating path. As seen in  FIG. 9A  atomized liquid is distributed at circular pattern having a large diameter. Upon rotating the housing  302  in the direction of arrow  326  (or respectively the vortex generating member  304 , in a reversed direction), the outlet nozzle  308  comes to a position in which it is opposite the lower vortex generating path  316 , whereby a narrower circular pattern of atomized liquid is distributed. Upon further rotation of the housing in the same direction (arrow  326 ), the longitudinal outlet nozzle  310  comes to a position in which it is in flow communication with the vortex generating path  314 , wherein the atomized liquid is emitted at a narrow, longitudinal pattern. 
     FIGS. 10 and 11  illustrate a further embodiment of the fogger in accordance with the present invention generally designated  400  and comprising a housing member  402  formed with an inlet  404  extending into a cavity  406  having a rectangular cross-sectional head  410  (best seen in  FIG. 10 ). 
   Head  410  is formed with four vortex generating paths  414  extending from cavity  406  through radial apertures  416  ( FIG. 11 ), similar to the vortex generating paths disclosed in previous embodiments. 
   An atomizing cap  420  has a receptacle  422  snugly receiving the square head  410  whereby opposite at least one vortex generating path  414  there is formed an outlet nozzle  424 , similar to the disclosure of the previous embodiments. However, it would be appreciated that the number of outlet nozzles may be lesser than the number of vortex generating paths for irrigating at a selective zone only. 
   Cap  420  is formed with radial recesses  428  for snapingly receiving radial projections  430  formed in housing  402  and an O-ring  436  is provided for sealing any interstice between the cap  420  and the head  410  to prevent wetting at the surrounding of the atomizer. 
   In operation, water entering inlet  404  emerges through apertures  416  and then flows through vortex generating paths  414  where it is vortexed and emerges then through outlet nozzles  424  in an atomized form as explained hereinbefore. 
   In connection with the embodiments of  FIGS. 8 and 9 , the artisan will appreciate that the devices may be used to distribute the atomized liquid in any distribution pattern, also distribution along the longitudinal axis of the device. 
   Further attention is now directed to another embodiment of the invention illustrated in  FIGS. 12 and 13 . The atomizer generally designated  500  is constructed of a housing  502  and a vortex generating member  504  snugly receivable within a suitable cavity  505  formed in the housing  502  (seen in  FIG. 13 ). Similar to the previous embodiments, the housing  502  is formed with two outlet nozzles  506  extending from the cavity  505 , which is in flow communication with an inlet  508  attachable to a water supply. The vortex generating member  504  is adapted for press fitting within the cavity  505  and is formed with two formed with two vortex generating paths  510  ( FIG. 12 ), each extending between an inlet  512  and a vortex generating portion  514 , which at the assembled state of the device extends opposite a corresponding outlet nozzle  506  of the housing  502 . The arrangement is such that liquid entering inlet  508  flows via inlets  512  into the vortex generating paths  510  such that it is forced to swivel within the vortex generating portion  514 , whereby as it leaves the outlets  506  it is in atomized form. 
   It is appreciated that the embodiment illustrated with reference to  FIGS. 12 and 13  may be modified into different embodiments, some of which have been discussed in connection with previous embodiments herein before. 
   Whilst preferred embodiments have been shown and described, it is to be understood that it is not intended thereby to limit the disclosure of the invention, but rather it is intended to cover all modifications and arrangements falling within the spirit and the scope of the invention, mutatis mutandis.