Patent Publication Number: US-6655606-B2

Title: Multiple nozzle tip assembly for airless paint sprayer gun

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to airless paint sprayers and, more particularly, to the design of tips used in the spray guns of such sprayers. 
     2. Description of the Prior Art 
     A typical airless paint sprayer includes a pump, a suction tube having one end coupled to the pump inlet and the free end insertable in a container of paint, and a high-pressure hose that connects the pump outlet to a spray gun. Typically, a check valve is installed at the pump outlet. The spray gun has a trigger which, when depressed, opens a valve to allow pressurized paint in the hose to flow through a nozzle in the gun tip. The paint is atomized as it exits the nozzle, allowing a painter to evenly apply the paint to a surface. Although there are dozens of manufacturers of airless paint spraying equipment, the function of the equipment is basically the same. Differences in the available equipment usually relate to the design and output capacity of the pump. The three most common types of pumps used in airless paint sprayers are diaphragm pumps, piston pumps and gear pumps. 
     The capacity of pump unit, the high-pressure hose length, and the number of spray guns connected to the pump unit will determine the maximum tip size. A sprayer having an output capacity of ½ gallon per minute (gpm) can comfortably support a single spray gun using a tip nozzle in the 0.015 to 0.021-inch (about 0.38 to 0.53 mm) diameter range. Required pump capacity increases by about the square of the nozzle size. 
     Referring now to FIG. 1, a spray gun  100  used in combination with airless paint spraying systems typically has a hollow, pistol-shaped body  101 . The body  100  incorporates a handle  102 , a squeezable trigger  103 , a trigger guard  104 , and an internal valve assembly  105 , controlled by the trigger  103 , that controls the flow of paint to an output barrel  106 . The handle  102  typically doubles as a housing for a removable screen filter (not shown). At the bottom of the handle  102  is a threaded coupling  107 , to which the high-pressure hose from the pump unit may be attached. Attached to the end  108  of the output barrel  106  is a spray tip assembly  109 . 
     Referring now to FIGS. 2 through 6, a typical spray tip assembly  109  includes a tip housing  201  having, at a first end thereof, a connector  202  that attaches to the end  108  of the output barrel and, at a second end thereof, a spray guard  203  that reduces the possibility of that a user of the equipment will inject paint into his body through the skin. The tip housing  201  generally incorporates a cylindrical bore  204  that is sized to receive a cylindrical shaft  301 , that is generally referred to as a spray tip. At the mouth of the cylindrical bore  204  on one side of the tip housing  201  is a semicircular recess  205 . When the spray tip assembly  109  is installed on the spray gun  100 , the cylindrical bore  204  is perpendicular to the axis  401  of the gun output barrel  106 . The cylindrical shaft  301  is sized for slidable entry into the cylindrical bore  204 , with minimal clearance so as to prevent leakage of paint between the cylindrical surface of the shaft  301  and the cylindrical surface of the bore  204 . For this particular prior art spray tip assembly  109 , the cylindrical shaft  301  is secured within the bore  204  with a semicircular spring clip  501 . 
     Still referring to FIGS. 2 through 6, the shaft  301  incorporates a single nozzle  302 , the axis of which is perpendicular to the axis  303  of the shaft  301 . At one end thereof, the shaft incorporates a handle  304 , which facilitates both removal of the of the shaft  301  from the tip housing  201  and rotation of the shaft  301  to reverse the nozzle  302  should it become clogged. The handle  304  may incorporate a stop  305  which, in combination with the semicircular recess  205 , allows the shaft  301  to be rotated only within an arc of 180 degrees. At one end of the arc, the nozzle  302  is positioned for spraying; at the other end of the arc, the nozzle  302  is positioned for unclogging. 
     Professional painters typically use several interchangeable tips of different sizes and/or different spray patterns at the same job site, the size and pattern of the tip being dictated by the particular application. For example, a tip with a 0.035-inch-diameter nozzle might be used for rapid application of latex base coats, while a tip with a 0.015-inch-diameter nozzle might be used for the painting of trim. In order to change to a different tip, the installed tip must be removed and stored for future use, and the desired tip installed in its place. The need to switch tips affords an opportunity for uninstalled tips to become lost. As the retail cost of each tip is about $US 30, the loss of multiple tips equates to a significant needless expense. There is also an additional economic waste related to the time required to switch out the tips. 
     U.S. Pat. No. 5,255,848 to Nolin C. Rhodehouse discloses a multiple orifice spray tip having reversible orifice cleaning capability for use with airless paint sprayers. A first embodiment spray tip offers first or second orifice by vertical movement of an orifice selection cylinder, while a second embodiment offers selection of a first or second orifice by rotation of the orifice selection cylinder about a vertical axis. There is a major disadvantage with each of these embodiments. The first embodiment requires an indexing tab to be attached with a screw at the end opposite the handle. This screw and indexing tab are problematic for two reasons. First, a screwdriver or other similar assembly tool is required to remove the spray nozzle. Therefore, the screwdriver must be carried to jobs and stored in a secure location. Secondly, construction sites are seldom neat and without clutter. Thus, if either the screw or the tab is dropped during disassembly or assembly, there is a fair likelihood that it will not be recovered. The disadvantage of the second embodiment is that tip manufacture is complicated by the nonlinear paths which the paint must take for each orifice. The additional complication will inevitably lead to production costs which are greater than for a tip which may be manufactured in a more straightforward manner. In addition, the nonlinear paint paths may affect the evenness or symmetricalness of the spray pattern. 
     Also available on the market is a product called DoubleShot®, which is a tip having two identically-sized orifices. Installation of a collar on the tip permits the orifice farthest removed from the handle to be used. Once the collar is removed, the orifice nearest the handle may be used. This product, however, does not address the need for multiple orifices of different sizes. 
     What is needed is a spray gun for airless paint sprayers which permits rapid changeover of spray nozzles without tools and, which does not require removable fasteners or other small parts which are readily misplaced or lost, and which permits both single and multiple orifice spray nozzle to be used with the same spray gun and tip guard. 
     SUMMARY OF THE INVENTION 
     The present invention provides a new spray tip assembly that may be used in combination with conventional spray guns for airless paint sprayers. The spray tip assembly incorporates a tip having multiple nozzles, each of which may be used independently. Several embodiments of the invention are contemplated. 
     For a first embodiment of the invention the shaft of the spray tip assembly incorporates multiple spaced apart nozzles and a handle at one end thereof. The shaft also incorporates a spring-loaded detent ball. The tip housing has a bore with a plurality of spaced-apart annular or semi-annular grooves, each of which, in conjunction with the spring-loaded detent ball, serves as a shaft locator for each of the nozzles. The grooves permit positioning of each of the nozzles in either a normal spraying position or in a reversed, unclogging position. 
     For a second embodiment of the invention, the tip housing incorporates three spaced-apart annular channels, all three of which are interconnected by a slot shaped to admit a stop tab attached to the shaft. More accurately, the outermost channel is really a semicircular recess, shown in the prior art description as item  205 , as it is open on one side. The stop tab may be indexed with any one of the channels, thereby serving to position the shaft so that each of the nozzles may be respectively and independently positioned for use. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a right-side elevational view of a typical prior art spray gun for an airless paint sprayer system; 
     FIG. 2 is an enlarged right side elevational view of the spray tip assembly of the spray gun of FIG. 1, with the spray tip removed; 
     FIG. 3 is an isometric view of a prior art single-nozzle spray tip; 
     FIG. 4 is a top plan see-through view of the spray tip assembly of the spray gun of FIG. 1, with the spray tip removed; 
     FIG. 5 is a top plan view of the spray tip assembly of the spray gun of FIG. 1, with the spray tip of FIG. 3 installed therein; 
     FIG. 6 is a front elevational view of the spray tip assembly of the spray gun of FIG. 1, with the spray tip of FIG. 3 installed therein; 
     FIG. 7 is an isometric view of a three-nozzle spray tip manufactured in accordance with the present invention; 
     FIG. 8 is a top cross-sectional plan view of a first embodiment spray tip housing for use in combination with the spray tip of FIG. 7, taken through the axes of the cylindrical tip receiving bore and of the paint inlet opening; 
     FIG. 9 is a is a top cross-sectional plan view of a second embodiment spray tip housing for use in combination with the spray tip of FIG. 7, taken through the axes of the cylindrical tip receiving bore and of the paint inlet opening; and 
     FIG. 10 is a side elevational view of the second embodiment spray tip housing of FIG.  9 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention provides a new spray tip assembly that may be used in combination with prior art spray guns for airless paint sprayers. The spray tip assembly incorporates a tip having multiple nozzles, each of which may be used independently. Several embodiments of the invention are contemplated, each of which will now be described with reference to the attached drawing figures. 
     Referring now to FIG. 7, a main embodiment multiple-nozzle spray tip shaft  700  manufactured in accordance with the present invention incorporates three aligned, spaced apart nozzles  701 A,  701 B and  701 C and a preferably non-removable handle  702  at one end thereof. The handle preferably incorporates a rotational stop tab  703 . The shaft  700  may also incorporate a spring-loaded detent ball  704 . The first embodiment spray tip shaft  700  may be used in combination with either the first embodiment spray tip housing  800  of FIG. 8 or the second embodiment spray tip housing  900  of FIGS. 9 and 10. 
     In the case of the combination of the first embodiment spray tip shaft  700  with the first embodiment housing  800 , the housing has a bore  801  equipped with a plurality of spaced-apart annular or semi-annular grooves  802 A and  802 B, each of which, in conjunction with the spring-loaded detent ball  704 , serves as a shaft locator for nozzles  701 A and  701 B, respectively. A semicircular recess  803 , in combination with the handle  702  and rotational stop tab  703 , serves to position nozzle  701 C. The grooves  802 A and  802 B permit positioning of each of the nozzles  701 A and  701 B in either a normal spraying position or in a reversed, unclogging position. Each of the grooves  802 A and  802 B may have a pair of depressions  804  (only one of which is shown for each groove), that are somewhat deeper than the grooves  802  for indexing the spraying and unclogging positions of the shaft  700 . 
     In the case of the combination of the first embodiment spray tip shaft  700  with the second embodiment housing  900 , the housing incorporates three spaced-apart annular channels  901 A,  901 B and  901 C, all three of which are interconnected by a slot  902  shaped to admit the stop tab  703 . More accurately, the outermost channel  901 A is really a semicircular recess, shown in the prior art description as item  205 , as it is open on one side. The stop tab  703  may be indexed with one of the channels  901 A,  901 B or  901 C, thereby serving to position the shaft  700  so that each of the nozzles  701 A,  701 B and  701 C may be respectively and independently positioned for use in a normal orientation for spraying, or a reversed orientation for unclogging. 
     Although only several embodiments of the invention has been heretofore described, it will be obvious to those having ordinary skill in the art that changes and modifications may be made thereto without departing from the scope and the spirit of the invention as hereinafter claimed.