Abstract:
A liquid sprayer with two side-by-side containers, an interconnecting bridge, and a nozzle insert positioned interiorly of the bridge. Alternatively, a two container piggyback liquid sprayer, a button actuator and a nozzle insert positioned interiorly of the button. One container is for product such as paint, etc., and the other container contains propellant. Very high product/propellant ratios are obtained. An intermediate portion of the nozzle insert has a venturi constriction with an internal propellant outlet orifice. Two product channels transverse to the nozzle insert longitudinal axis overlap the internal outlet orifice by approximately one-half. An outer frustoconical surface surrounds the internal venturi constriction outlet. An expansion chamber diameter is greater than the diameter of both the venturi constriction outlet orifice and the outer frustoconical surface adjacent this orifice. The venturi constriction outlet orifice is longitudinally spaced from the expansion chamber a distance to substantially prevent the propellant gas cone passing into the transverse product channels. The transverse product channels are quasi-rectangular with areas greater than the venturi constriction outlet orifice. Internal bridge or button spaces extend about the intermediate portion of the nozzle insert. Other significant dimensional relationships are set forth.

Description:
This application is a divisional application of Ser. No. 09/030,712, filed Feb. 26, 1998, now U.S. Pat. No. 6,062,493. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to sprayers for spraying paint and other liquids from a first container by use of pressurized propellant gas carried by and released from a second container. 
     BACKGROUND OF THE INVENTION 
     Paint sprayers, wherein the paint is contained in a first container and the propellant gas is contained in a second container, have advantages over single aerosol cans having both the propellant and paint contained therein. The latter form of packaging requires extensive inventories of aerosol cans with various colors, and the sales of a given color of paint may not be sufficient to warrant the production, marketing and stocking of aerosol cans with that given color of paint. The same may be said for other types of products marketed in aerosol cans, for example different types of insecticides, etc. However, in a two-container, hand-held spraying system of the aforementioned type, the product container may be used interchangeably with different colors or types of paints since the product container is detachable from the remainder of the spraying system. After spraying a particular color or type of paint placed in the product container, the product container is detached and cleaned so as to be ready to be refilled with a different (or the same) color or type of paint to be next sprayed. The propellant container is likewise detachable from the spraying system, so that when the propellant has been used up in the propellant container, a new container filled with propellant may be attached to the spraying system. As can be seen, such systems have considerable versatility and have become popular. 
     One type of two container system commercially available utilizes two side-by-side containers connected together by a bridge member. Propellant from the propellant can flows through the bridge and out the bridge through a nozzle that overlies a product tube extending down into the product container. The fast flow of the propellant over the end of the product tube creates a lowered pressure at that point such that the air pressure acting on the liquid in the product container forces product up the product tube and into the stream of propellant gas. In such systems a very low product to propellant ratio is obtained for reasons including that the pressure is only moderately lowered over the top of the product tube. Modifications of this type of side-by-side system have the bridge with its exit nozzle positioned forward of the top of the product tube, and with a form of nozzle insert positioned in the bridge near the exit nozzle. The propellant gas passes through the nozzle insert and likewise acts to lower the pressure over the end of the product tube to cause product flow into the stream of propellant gas. Such a latter system with a nozzle insert has a better product to propellant ratio, for example, of the approximate order of three to one, but there is still an excessive use of propellant. The nozzle inserts of such systems generally are poorly designed and do not create a sufficient vacuum over the top of the product tube. 
     A further type of two container system has the propellant container mounted piggyback on top of the product container. Product from a tube in the bottom container can flow up through a tube in the propellant container to an actuating button on the top of the propellant container. A nozzle insert in the button, generally operational as previously set forth, has resulted in the obtaining of enhanced product to propellant ratios of five or six to one for products of the viscosity of water. Such systems would benefit from a still further enhanced product to propellant ratio. 
     SUMMARY OF THE INVENTION 
     The present invention provides an embodiment of a liquid sprayer system having the above-described two side-by-side containers, an interconnecting bridge, a nozzle insert positioned interiorly of the bridge, and obtainable product to propellant ratios of approximately thirteen to one for products of the viscosity of water. 
     The nozzle insert has a rearward portion in fluid contact with a propellant channel in the interconnecting bridge; an intermediate portion containing a venturi constriction with an outlet orifice from which propellant may exit and at least two product channels adjacent the venturi constriction and extending substantially transverse to the longitudinal axis of the nozzle insert; and a forward portion containing an expansion chamber with an entrance diameter significantly larger than the diameter of the venturi constriction. The expansion chamber has a length sufficient to not substantially disrupt the vacuum established by the venturi constriction outlet at the transverse product channels. 
     An interior bridge space extends about the intermediate portion of the nozzle insert and also is in fluid communication with both an opening into the bridge from the product container and the transverse product channels. The transverse product channels extend longitudinally forward of the venturi constriction and also extend longitudinally rearwardly to longitudinally overlap the venturi constriction, the latter overlap being by approximately half the longitudinal dimension of the product channels in an embodiment of the present invention. A smoothly tapering, for example frustoconical, surface surrounds the venturi constriction outlet, the smaller forward outer diameter of the tapering surface being less than the entrance diameter of the expansion chamber. A smooth product flow extends from the product chamber into the gas stream exiting the venturi constriction orifice. 
     The venturi constriction outlet is longitudinally spaced from the entrance of the expansion chamber such that the circumference of the envelope of a cone of propellant gas exiting the constriction outlet remains substantially equal to or less than the circumference of the expansion chamber entrance until the cone enters the expansion chamber. If this cone becomes larger in circumference, the propellant gas exiting the constriction outlet will pass in part up into the transverse product channels to create eddy circuits and lower the vacuum created by the venturi constriction, thereby lowering product to propellant ratios. 
     In the present invention, the transverse product channels have areas substantially greater than the area of the venturi constriction outlet orifice, and for increased product flow, may have an outer opening of a shape having both curved and linear components forming a quasi-rectangular shape. The nozzle insert also is a unitary member in the embodiment described. 
     An alternative embodiment of the present invention utilizes a two container piggyback liquid sprayer system, wherein the same aforedescribed nozzle insert is correspondingly mounted within a space in the button actuator on top of the propellant container. Propellant to product ratios of water viscosity products are obtainable of the order of approximately nine to one. 
     Other features and advantages of the present invention will be apparent from the following description, drawings and claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a side elevation view of a liquid sprayer having two side-by-side separate containers and an interconnecting bridge; 
     FIG. 2 is a top plan view of the interconnecting bridge of the sprayer of FIG. 1; 
     FIG. 3 is a longitudinal cross-sectional view of the interconnecting bridge of the sprayer of FIG. 1 taken along line  3 — 3  of FIG. 2; 
     FIG. 4 is a fragmentary cross-sectional view of a portion of FIG. 3 but on an enlarged scale to illustrate the nozzle insert of the present invention mounted within the interconnecting bridge; 
     FIG. 5 is a cross-sectional view of solely the nozzle insert shown in FIG. 4; 
     FIG. 6 is a top plan view of the nozzle insert shown in FIG. 5; 
     FIG. 7 is a transverse cross-sectional view of the nozzle insert taken along lines  7 — 7  of FIGS. 5 and 6; 
     FIG. 8 is a front elevation view of the nozzle insert shown in FIG. 5; 
     FIG. 9 is a side elevation view of an alternative form of liquid sprayer having two separate containers mounted one on top of the other, and in which the nozzle insert of the present invention may be used; and 
     FIG. 10 is a fragmentary cross-sectional view on an enlarged scale of the top portion of FIG. 9, taken in a vertical diametrical plane and illustrating the nozzle insert of the present invention mounted in an actuating button. 
    
    
     DESCRIPTION OF EMBODIMENTS 
     FIGS. 1-3 illustrate generally a liquid sprayer  10  having a container  11  for material to be sprayed, such as paint, a container  12  containing an aerosol propellant, and an interconnecting bridge  13 . The aerosol propellant may be in the form of a partially liquified propellant gas under substantial pressure. Interconnecting bridge  13  is molded of plastic and can be snapped onto container  12 . Container  12  has a conventional aerosol valve mounted at its top into a conventional aerosol mounting cup. Bridge  13  in its position directly above container  12  may have flexible depending lugs that fit within the conventional aerosol mounting cup to retain the bridge  13  on container  12 . Alternatively, a depending circular flange from the bridge may snap over the outside of the mounting cup. Bridge  13  also has a hinged depressible member  14 , which when pressed by the finger of a user of the sprayer actuates the aerosol valve to release propellant gas from the aerosol container  12  up into an internal channel  15  in bridge  13 . The valve stem of the aerosol valve fits into a central opening in the lower surface of go. depressible member  14 , so that when member  14  is pressed downwardly, propellant gas flows up the aerosol valve stem into bridge channel  15  as shown by the arrow in FIG.  3 . 
     When gas is released from aerosol container  12 , it flows forwardly along the internal channel  15  to an inlet of a nozzle insert  30  contained within the bridge  13 . The outlet of a venturi constriction within nozzle insert  30  draws product into the bridge  13  from product container  11 , the bridge portion over the product container having screw threads to nest with screw threads on the top of container  11 . One end  17   a  of a tube  17  extends nearly to the bottom of container  11 , and the other end  17   b  of tube  17  surrounds a tubular part  18  of bridge  13  which part  18  has an internal channel providing a flow path for product into the bridge and ultimately to a position adjacent the venturi constriction outlet. The outlet of the venturi constriction with its reduced pressure creates a vacuum, and the air pressure over the liquid in container  11  forces product from container  11  up tube  17  into the bridge. The product and propellant gas are mixed and exit sprayer  10  as a spray. 
     Referring now to FIGS. 4-8, the novel molded plastic nozzle insert  30  is illustrated, also including its particular interrelationship with bridge  13  as shown in FIG.  4 . These structures will first be described, followed by a description of the more critical aspects thereof. 
     Nozzle insert  30  extending along its central longitudinal axis has a rearward portion  31  containing channel  32  leading forwardly toward the venturi constriction, and forward portion  33  containing an expansion chamber  34 . Intermediate portion  35  of nozzle insert  30  contains the venturi constriction and two transverse product channels  37 . 
     FIG. 4 illustrates the nozzle insert  30  contained within the interconnecting bridge  13  in a forward end opening  38  thereof. Both the outer surfaces of nozzle insert  30  and the inner surfaces of bridge end opening  38  are circular in cross-sectional planes perpendicular to the central longitudinal axis of nozzle insert  30 , except as otherwise shown or described hereinafter in relation to the entrance to product channels  37 . The nozzle insert  30  may be inserted from the forward end of sprayer  10  and captured by a circumferential bead on the side wall of the opening  38  in the bridge  13 . Bridge  13  is shown in FIG. 4 having the depending tubular part  18  over which is fitted the end  17   b  of aforementioned product tube  17  extending into container  11 . Product flows up tube  17  and into the cylindrical space  39  within the bridge surrounding the nozzle insert  30 . From this cylindrical space  39 , product flows into the two diametrically opposite product channels  37 , further described below, extending to the interior of the nozzle insert  30 . This flow of product is shown by the arrows in FIG.  4 . Frustoconical surface  40  of bridge  13  serves to assist in directing the product flow inwardly toward product channels  37 . Cylindrical channel  32  of nozzle insert  30  is of course in axial communication with internal gas channel  15  of bridge  13 . 
     Referring now to FIGS. 5-8 illustrating the nozzle insert  30  per se, it will be observed that cylindrical channel  32  extends forwardly to converging channel  50  and narrowed terminal cylindrical channel  51  forming the venturi constriction and having a circular constriction outlet orifice  52 . The diameter of the constriction outlet orifice  52  for the gas propellant from container  12  is significantly smaller than the diameter of cylindrical expansion chamber  34 , as will be hereinafter discussed. Further, the forward end of channel  51  is spaced a particular distance in the longitudinal direction from the circular edge  53  of forward portion  33  surrounding expansion chamber  34 , also as further discussed below. 
     It will be noted that the two product channels  37  extend generally laterally inwardly toward the longitudinal axis of nozzle insert  30 . Product channels  37  extend longitudinally in a forward direction from gas outlet  52  to forward portion  33  of nozzle insert  30 , and extend longitudinally in a rearward direction from gas outlet  52  to significantly overlap the venturi constriction and its outlet. This amount of overlap is approximately half the longitudinal span of the product openings  37  in the embodiment shown. The forward surfaces  54  of the product openings  37  extend inwardly and rearwardly as shown in FIGS. 5 and 6. The rearward surfaces  55  of product openings  37  extend forwardly and inwardly as shown in FIGS. 5 and 6. Frustoconical or otherwise smoothly tapering surface  56  that surrounds channel  51  also serves as an inwardly and forwardly directed continuation surface of rearward surfaces  55  of the product openings  37 , serving to smoothly direct the product flow inwardly and forwardly to mix with the propellant in expansion chamber  34 . 
     Further referring to product openings  37 , reference is made to FIG.  6 . Each product opening  37  at its outer opening is in part circular (in the longitudinal direction) and in part rectangular (in the transverse direction), the latter aspect to provide for a larger product flow than would be available with a fully circular opening for the same given longitudinal direction. FIG. 7 provides a further view of product channels  37  extending into nozzle unit  30 , and FIG. 8 illustrates the front end exit of nozzle insert  30 . 
     FIG. 9 illustrates an alternative form of liquid sprayer, having an aerosol propellant container  60  screwed onto liquid container  61  containing the product to be sprayed. Actuating button  62  when pressed downwardly serves to actuate the sprayer and is shown in enlarged detail in FIG.  10 . Tube  63  carries liquid product up through the tube extending upwardly through container  60  to exit the upwardly extending central portion  64   a  of the aerosol valve stem  64  into the button  62 , the button having a central opening  65  fitting over the upwardly extending central portion of  64   a . The valve stem  64  also has three peripheral orifices  66  spaced one hundred and twenty degrees around the circumference of the valve stem  64  and exiting below portion  64   a , one such orifice being shown in the cross-section of FIG.  10 . Orifices  66  are valved by a conventional aerosol valve to the propellant in propellant container  60  when the valve stem is depressed by button  62 . 
     Also contained within button  62  in its end opening  67  is the identical nozzle insert  30  of FIGS. 5-8 described above. When button  62  is depressed, the product flows into cylindrical space  68  surrounding the nozzle insert  30 , and propellant flows up circumferentially extending channel  69  in button  62  overlapping orifices  66  and into the rearward end of nozzle insert  30 . The nozzle insert functions exactly as described above in relation to FIGS. 4-8. Similar systems have been previously used as generally shown in FIG. 9, obtaining product to propellant ratios of the order of five or six to one for a product of water viscosity. However, the sprayer of FIGS. 9-10 having the nozzle insert  30  of FIGS. 4-8 and the button internal configuration of FIG. 10 has obtained product to propellant ratios of approximately nine to one for a product of water viscosity. 
     A number of elements of the above description and drawings are believed to be significant in obtaining the remarkable product to propellant ratios obtained in the present invention. Referring to FIGS. 4-8, it is presently believed to be important that: 
     (a) The longitudinal space from gas outlet orifice  52  extending forwardly to the entrance to expansion chamber  34 , beginning at circular edge  53 , needs to be dimensioned such that the outer circumference of the expansion cone of propellant gas exiting orifice  52  essentially remains less than or equal to the circumference of circular edge  53  until the gas has passed forwardly into the expansion chamber  34 . This is shown diagrammatically in dotted line in FIG.  5 . If this cone circumference becomes greater than this before its forward travel reaches circular edge  53 , the high speed gas will pass in part back up into transverse product channels  37  to create eddy currents and lower the vacuum created by the venturi constriction. This of course will lower the product to propellant ratios desired. 
     (b) Gas outlet orifice  52  should have a significantly smaller diameter than the diameter of expansion chamber  34 , both to allow for expansion and mixing and further to assure, in conjunction with the longitudinal space discussed in (a) above, that the circumference of the gas expansion cone does not significantly exceed the diameter of circular edge  53 . Further, gas outlet orifice  52  should be sized in relation to the diameter of expansion chamber  34  and product channels  37  to obtain the desired product to propellant ratios. 
     (c) A significant amount of longitudinal overlap of transverse product channels  37 , rearwardly from circular outlet orifice  52 , is needed. As discussed above, this overlap is approximately half the longitudinal span of the product openings  37  in the embodiment described. 
     (d) The rearward surfaces  55  of the product openings  37 , and the frustoconical surface  56  surrounding channel  51 , should provide a smooth product flow through the product openings  37  and into the gas flow from gas outlet orifice  52 . Sharp protruding edges along surfaces  55  and  56  may result in eddy currents in the product flow, resulting in a decrease in the desired product to propellant ratio. The frustoconical surface  56  should terminate in the forward direction at leading edge  57  having a diameter less than that of the diameter of circular edge  53  of expansion chamber  34 , to flow the product from product channels  37  down into the gas stream exiting gas outlet orifice  52 . 
     (e) The product channels  37  should be of a sufficient size to achieve the desired product to propellant ratios. The product openings can be enlarged as shown in FIG. 6 to have both circular and rectangular components as earlier described above. More product flow can then be obtained for a given longitudinal dimension of product channels  37 , and a larger diameter product tube  17  can be used. Product tube  17  has an outer diameter of 0.158 inches in the embodiment here described. 
     (f) The longitudinal length of expansion chamber  34  needs to be sufficiently long so as to obtain proper expansion and mixing of the product and gas and also sufficiently long so as not to adversely affect the desired vacuum at product channels  37 . However, the expansion chamber  34  should not be so long so as to create frictional back pressure resulting in less desirable spraying characteristics. 
     (g) The diameter of inlet  32  to the nozzle insert  30  needs to be sized in relation to the remaining diameters in the nozzle insert in order to obtain the desired product to propellant ratios. 
     The dimensions of a nozzle insert for a particular embodiment are set forth below. However, it should be understood that these dimensions may vary for embodiments constructed to spray products of varying viscosities and other characteristics. As can be seen, however, these dimensions are interrelated. It is presently believed that different dimensions for the orifices of the nozzle insert  30  described above will remain in substantially constant ratios with each other according to their respective areas. Likewise, the length of the expansion chamber  34  will probably vary in proportion to the orifice areas. 
     Dimensions of An Embodiment Of Nozzle Insert  30 : 
     Diameter of Channel  32 : 0.030 inches 
     Diameter of Orifice  52 : 0.012 inches 
     Diameter of Expansion Chamber  34 : 0.032 inches 
     Longitudinal Dimension of Each Channel  37 : 0.040 inches 
     Transverse Dimension of Each Channel  37 : 0.050 inches (at diameter) 
     Length of Nozzle Insert  30 : 0.369 inches 
     Length of Channel  32 : 0.212 inches 
     Length of Channel  50 : 0.066 inches 
     Length of Channel  51 : 0.018 inches 
     Length of Expansion Chamber  34 : 0.049 inches 
     Maximum Outer Diameter Forward Portion  33 : 0.185 inches 
     Outer Diameter Rearward Portion  31 : 0.095 inches 
     Angle of Surface  56  to Longitudinal Axis: 17 degrees 
     Angle of Surfaces  55  to Transverse Axis: 11 degrees 
     Longitudinal Distance Edge  57  to Edge  53 : 0.016 inches 
     In the above embodiment of the present invention, as shown in the drawings and described, the design of the nozzle insert  30  combined with the tight fitting positioning thereof within bridge  13  or button  62 , results in high vacuums being established at the transverse product channels  37  of the order of 40-50 centimeters of mercury, for example. The vacuum, combined with the other aforedescribed significant design features, results in remarkable product to propellant ratios of the order of approximately thirteen to one for products having the viscosity of water. This ratio is well in excess of that found in currently available paint sprayers and the like. Further, vinyl and enamel paints can be satisfactorily sprayed with sprayers of the present invention. 
     It will be appreciated by persons skilled in the art that variations and/or modifications may be made to the present invention without departing from the spirit and scope of the invention. The present embodiment is, therefore, to be considered as illustrative and not restrictive.