Abstract:
A low-flow-rate sprayer assembly is provided, wherein additive from a container is entrained in a stream of carrier fluid passing through a venturi. The pressures created by flow through the venturi actuate a release valve on the container and entrain the additive in the carrier fluid.

Description:
FIELD OF THE INVENTION 
   The invention relates generally to mixing and dispensing sprayers and more particularly to aspiration type sprayers for use in dispensing a liquid based chemical from a valved container into a carrier fluid. 
   BACKGROUND OF THE INVENTION 
   Every year thousands of gallons of chemicals such as fertilizers or pesticides are applied to crops, plants, lawns, flowers, vegetable gardens and other organic type vegetation. Such chemicals are often sold to the consumer in the form of a concentrated liquid, and therefore are extremely hazardous to the consumer end user and environment in general. Accordingly, these concentrated liquids are marketed in sealed valved containers. 
   However, the need exists for a sprayer that can cooperatively engage the container and entrain the chemicals or solution from the container for dispersion. The need also exists for a sprayer that can employ relatively low flow rates to access and disperse the chemicals from the container. 
   SUMMARY OF THE INVENTION 
   The present invention provides a low-flow rate aspirator type sprayer, configured to be removably interlocked with a single-use pre-filled container. The container includes a valve for selectively permitting passage of material from the container. The sprayer is connected to a source of a carrier fluid such as a tank sprayer. A specific configuration of the present invention provides sufficient aspiration at relatively low flow rates to access the material in the container and entrain the material for dispersion. 
   The sprayer includes a housing, which encloses a passageway having a venturi. The passageway is fluidly connected to a plunger which is moveably connected to the housing between a retracted position and an actuating position.  The plunger has a duct there through to provide a path for material from the container to pass to the passageway. 
   When purchased by the user, the container is sealed by a valving mechanism which is held in a closed position by a bias mechanism, such as a spring. The valving mechanism provides an exit from the container when properly actuated. A dip tube extends from the valving mechanism and is sized to be immersed in the additive until the additive is depleted. 
   A superstructure of the container has a flange which can interlock with the sprayer housing. With the sprayer and the container interlocked together, the plunger is aligned with the valving mechanism. When water is caused to flow through the passageway and the venturi, a resulting high pressure is created upstream of the venturi constriction, this relatively high pressure is exposed to the plunger to urge the plunger against the valving mechanism to open a flow path from the container to the venturi. The water flow also produces a reduced pressure at the constriction of the venturi which allows an atmospheric pressure acting on the additive in the container to push the additive through the dip tube and into the flow passing through the passageway. 
   That is, once the plunger is actuated, the pressure differential between the reduced pressure in the venturi and the atmospheric pressure acting on the material (additive) in the container causes the additive to be pushed up through the dip tube, the valving mechanism and the plunger until it enters the stream of carrier liquid in the venturi. This upward flow of additive is driven by the atmospheric pressure above the additive, which is greater than the pressure at the point where the additive exits into the venturi. 
   The concentrate additive enters the low-pressure area of the venturi and mixes with the water as it flows into the diverging section of the venturi, extension and nozzle tip. At the venturi divergence, the high pressure is restored and is applied through the extension to the nozzle tip. This high pressure at the tip  allows for the ability to increase the velocity at the nozzle and provide the shear stresses needed to form droplets in a spray pattern. 
   The invention, then, provides that the pressure required for the plunger to actuate the valving mechanism of the container is supplied by a relatively high pressure in the flow of carrier fluid resulting from the flow of the carrier fluid through the venturi, eliminating the necessity for a mechanical device to be incorporated into the nozzle. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic of a spraying apparatus. 
       FIG. 2  shows in cross-section a spray assembly in a non-operative position, including a spray nozzle and a container. 
       FIG. 3  shows a close-up of a portion of  FIG. 2 . 
       FIG. 4  shows the spray nozzle in cross-section, in an operative position. 
       FIG. 5  shows a venturi in cross-section. 
       FIG. 6  is a top plan view of a plunger. 
       FIG. 7  is a cross section of the plunger taken along line  7 — 7  of  FIG. 6 . 
       FIG. 8  is a perspective view of a portion of the plunger. 
       FIG. 9  is a perspective view of a check valve. 
       FIG. 10  is a plan view of a flexible seal. 
       FIG. 11  is a cross-section of the flexible seal taken along line  10 — 10 . 
       FIG. 12  is a cross-section of a portion of a reconfigured venturi from a second embodiment of the spray nozzle. 
       FIG. 13  is a cross-section showing a reconfigured plunger engaged with the venturi of  FIG. 12 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to the drawings, a spraying apparatus  10  shown schematically in  FIG. 1  includes a fluid source  20  and a sprayer assembly  30 . The spraying  apparatus  10  cooperates with a chemical container  50  to withdraw and disperse an additive (chemical)  58  from the container  50 . 
   The fluid source  20  is typically a tank which can be pressurized by hand, and also includes flexible hose  22  with a shutoff  24 , and a first connector fitting  26 . However, it is understood the fluid source  20  may be any of a variety of structures including pack back tanks, hand portable tanks or even tractor transported tanks. 
   In the preferred embodiment, the sprayer assembly  30  shown in  FIG. 2  cooperates with the container  50  which has a neck  51  enclosed by a superstructure  52 . The container  50  includes an interlock portion  54 . The container  50  holds an additive (chemical)  58  which, when the sprayer assembly  30  is functioning, is drawn into a fluid stream in the spray nozzle  40  to be diluted to a predetermined degree and sprayed on a selected surface. 
   The sprayer assembly  30  includes a nozzle  40 , having a housing  42  and an interlock flange  44  which releasably engages with the interlock portion  54 . A second connector fitting  56  couples with the first connector fitting  26  to provide a fluid-tight joint between the source  20  and the spray nozzle  40 . 
   An important feature of the sprayer assembly  30  is a passageway  62  including a venturi  60 , viewed in the cross-section of  FIGS. 4 and 5 . A wide entry  64  and a first tapered region  66  lead to a constriction  68 , and a second expanding tapered region  70  terminates at an exit  72  which has a similar diameter to the entry portion  64 . Each of the tapered regions  66  and  70  has respectively a steeply tapering portion  74  and  76 , a less steeply tapering portion  78  and  80 , and a corresponding transitional portion  82  and  84  between them. The exact profile of the venturi  60  is determined by the quantitative fluid flow and pressure requirements. Qualitatively, the general characteristics of the venturi  60  provide that fluid which enters at a certain rate must increase its flow velocity as it passes through the constriction  68  and decrease its flow velocity as the passageway  62   widens again. The fluid pressure must correspondingly fall as the flow passes through the constriction  68  and increases again downstream of the constriction. That is, the flow is governed by Bernoulli&#39;s equation which states that along a flow line, the static pressure plus dynamic pressure remain constant. 
   The housing  42  has a depending boss  100 , providing an open-ended channel  102  which communicates with the passageway  62 , and has a diameter comparable with that of the constriction  68 . Concentric with the boss  100  is a skirt  104  which depends from the body of the housing  42 , extending approximately the same distance as the boss  100 . 
   A space  106  between the boss  100  and skirt  104  accommodates an actuator or plunger  110 , which has a generally cylindrical shape and includes an open-ended axial channel  112 , as seen in  FIGS. 6 and 7 . The plunger is movable between a retracted position and an actuating position. An upper portion  114  of the plunger  110  has a cylindrical cavity  116  and is sized so that it can slidingly engage the housing  42  intermediate the boss  100  and the skirt  104 . At the lowest part of the cavity  116  is a seat  118  wherein is located a check valve  130  illustrated in  FIG. 9 . The check valve  130  has the form of a ring  132  having an aperture  134  and a hinged flapper portion  136 . The check valve  130  is biased to a default open position, to permit flow from the sprayer assembly  30  to the container  50 . 
   A lower portion  120  of the plunger  110  has vertical strengthening ribs  122  spaced around its perimeter. Also provided on the lower portion has a stop  126  which limits downward travel of the plunger  110  when it contacts the interior surface of the housing  42 , and ensures that the upper portion  114  of the plunger  110  remains intermediate and engaged with the boss  100  and the skirt  104 . 
   A conduit  86  extends from an entry point  88 , at a relatively high pressure region of the venturi  60 , to an exit point  90  which is inside the space  106 , and diverts some of the incoming fluid thereto. In effect, the conduit  86  allows the  fluid pressure at the entry point  88  to be transmitted to the plunger  110 . The application of this pressure on the plunger  110  urges it downward to actuate the valving of the container  50  in a manner which will become clear. In an alternative configuration, a flexible seal  92  is located to inhibit migration of fluid beyond the plunger  110 . 
   The seal  92  has a generally circular shape when viewed from above, as seen in  FIG. 10 . When viewed in profile, the seal  92  exhibits a cross-section having the double-cup shape of  FIG. 11 . A smaller, inverted portion  94  of the seal  92  is sized to be received by a recess  96  which is provided at the upper end of the plunger  110 , as best seen in  FIGS. 7 and 8 . In profile, the recess  96  becomes wider as its depth increases, allowing the inverted portion  94  of the seal  92  to be securely engaged therein. An upper portion  98  of the seal  92 , when not constrained has an outer circumference slightly greater than the inside circumference of the skirt  104 , and an inner circumference slightly smaller than the outer circumference of the protuberance  100 . Both the outer and inner circumferences of the seal  92  are in constant contact with the corresponding surfaces of the venturi  60 , and the passage of fluid is precluded thereat, while the plunger  110  remains free to be moved up and down between the retracted position and the actuating position. 
   Referring to  FIG. 2 , a carrier fluid input tube  140  passes through the housing  42  and is inserted into the entry portion of the venturi  60 , being sealed therein using an O-ring  142 . Outside the housing,  42 , the input tube  140  terminates at the second connector fitting  56 , which couples with the first connector fitting  26  as previously indicated. Similarly, an output tube  144  is sealed in the exit portion  72  using a second o-ring  146 . The output tube  144  passes through the housing, beyond which it extends some appropriate distance and terminates at a nozzle tip  148 , which can be chosen according to the pattern of spray desired.  
   Prior to the sprayer  30  being attached to the container  50 , the container contents are sealed therein by a valving assembly  160  which is enclosed by a collar  53  of the superstructure  52 . As best seen in  FIG. 3 , the valving assembly  160  extends downward into the container  50  through the neck  51 , and is threadedly joined thereto through an intermediate structure  55 . When the sprayer assembly  30  is attached to the container  50 , the plunger  110  is brought into contact with a movable member  161  of the valving assembly  160  against the opposition of a spring  162 . It is not necessary for the purposes of this application to provide a detailed description of the valving assembly  160 ; however, it is pertinent to indicate that the valving assembly  160  has an outlet valve  164  which is seated in an orifice  166  of an additive inlet tube  168  and acts as a gate. It is displaced upward by additive as it enters through a dip-tube  170  from the container  50 , but any back flow is precluded since the concomitant downward pressure would immediately cause the outlet valve  164  to be re-seated in the orifice  166  to provide a seal. 
   The spray assembly  30  is attached to a carrier fluid source which provides a low flow rate of water, typically in the range up to about 1.5 gallons per minute (approximately 6 liters per minute). In one configuration, the source  20  is a tank sprayer which can be pumped by hand to provide an internal pressure to eject the water, although a garden hose could also be used if a suitable flow limiter were employed. 
   Operation 
   To prepare the assembly for use, the container  50  containing additive is locked in position on the sprayer  30 , bringing the plunger  110  into contact with the valving assembly  160 . In the absence of any further pressure, the opposing force of the spring  162  ensures that the plunger  110  remains in its uppermost, retracted, position. At this point, the sprayer assembly  30  has the configuration shown in  FIG. 2 , with the plunger stop  126  elevated above the interior surface of the housing  42 .  
   A shutoff  24  at the source  20  is turned on to allow the flow of carrier liquid, water, to commence. As the water passes through the venturi  60 , the water from the conduit  86  exerts a relatively high pressure on the upper surface of the plunger  110 . The water being at a relatively high pressure corresponding to the position in the venturi  60  where the conduit has its entry point  88 , there is sufficient pressure to overcome the opposition of the spring  162  and causes the plunger  110  and the movable member  161  of the valving assembly  160  to be downwardly displaced together to the actuating position, thereby unsealing the container  50  so that additive  58  can exit. The plunger  110  is now in the position illustrated in  FIG. 4 , the stop  126  being in contact with the interior of the housing  42 , which limits further downward travel. 
   Meanwhile, the water flowing past the constriction  68  has a lower pressure than the interior of the container  50 , providing a driving force for the additive  58  to be expelled therefrom. The pressure drop between the container  50  and the area of the constriction  68  causes the outlet valve  164  and the check valve  130  to open, and additive  58  is drawn up through the dip tube  170  and into the venturi  60 , wherein it enters the carrier liquid (water) stream and is mixed with the water downstream from the constriction  68 . The proportion of additive to water is determined by characteristics of the venturi  60  in a manner which is well known in the art and which is not the subject of this invention. 
   When no further spraying is required, the shut-off  24  at the source is closed to stop the flow of water through the passageway and venturi. The upward force of the spring  162  is now sufficient to return the movable member  161  and the plunger  110  to their uppermost positions. The outlet valve  164  and the check valve  130  close, and entry of residual water from the venturi  60  into the container  50  is precluded. If the contents of the container  50  are exhausted or are no longer  currently required, the container  50  can be separated from the spray nozzle  40 , and replaced if desired by another container which has either the same or a different additive. 
   In the foregoing preferred embodiment, a positive pressure is communicated from a relatively high-pressure region of the venturi to a portion of the plunger  110 , which is thus urged downward to the actuating position. In another embodiment shown in  FIGS. 12 and 13 , a reconfigured plunger  180  is actuated by a negative pressure communicated from a low-pressure region of a reconfigured venturi  180 , shown in  FIG. 12 . A conduit  192  is provided in the venturi  190  between a low-pressure point  194  and a point  196  at which it meets a part of the space  106  between the protuberance  100  and the skirt  104 . A vent  198  passes through the skirt near the top of the space  106 . A second seal is also provided on the bottom of the plunger  180 . 
     FIG. 13  shows the reconfigured plunger  180  slidingly engaged with the venturi  190  in the space  106 . The plunger  180  has a sliding portion  182  which is joined to the lower portion  120  by a narrower stem portion  184 . The flexible seal  92  is secured to the sliding portion  182  in the same manner as it is attached to the plunger  110  of the first embodiment. The plunger  180  can travel up and down within the space  106  such that the upper and lower limits of travel are between the conduit point  196  and the vent  198 . 
   When the spray nozzle is activated, a low pressure is established at point  194  and transmitted through the conduit  192  to the portion of the space  106  which is below the sliding portion  182 . The presence of the vent  198  maintains the portion of space  106  which is above the sliding portion  182  at atmospheric pressure. The resulting pressure difference urges the plunger  180  downward. 
   The spraying apparatus  10  of the invention has several advantages compared with other low-flow spraying systems. In other spraying systems, additives must frequently be diluted by hand, with the possibility of spills,  mistakes and miscalculations. Other tank spraying systems require a mixed additive-water solution to be present in the tank, whereas in the present invention, the tank need contain only water. Rinsing out a tank between uses of different chemicals is much more laborious than the trivial task of purging a small remnant of solution from a spray nozzle. Furthermore, the spray nozzle of the present invention does not require its own shutoff, since flow of additive commences as a result of the pressure differences in the sprayer assembly  30  which only exist when water flows through the venturi. Spraying is simply initiated by operating a shutoff  24  which is already present at the source  20 . The absence of an on-off control in the spray nozzle  40  renders it more simple and economical to manufacture. 
   While the invention has been described in connection with certain embodiments, it is not intended to limit the scope of the invention to the particular form set forth, but on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.