Abstract:
An improved paint spray gun, including high volume and low pressure air paint spray guns, siphon-type paint spray guns, and gravity-fed-type spray guns, in which the spray pattern may be adjusted single-handedly with the gripping hand while in use. The invention includes a thumb and/or finger adjustable wheel rotatably mounted in the spray gun that is accessible while gripping the spray gun and may be used to adjust the spray characteristics of paint or similar liquid being sprayed.

Description:
RELATED APPLICATIONS 
       [0001]    There are no related applications. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISC APPENDIX 
       [0003]    None. 
       FIELD OF THE INVENTION 
       [0004]    The invention relates to improved paint spray guns, including spray guns using low pressure and high volume air for atomizing the paint, whereby their spray pattern may be adjusted single-handedly with the gripping hand while in use. The apparatus includes a thumb and/or finger adjustable wheel that is accessible to adjust the spray characteristics of the paint or similar liquid being ejected therefrom. 
       BACKGROUND OF THE INVENTION 
       [0005]    Spray guns, especially those used with spray painting systems, atomize the liquid paint by means of air which enters a nozzle area via a chamber surrounding a fluid nozzle. The atomizing air is then impinged at the end of the chamber and exits via a central aperture located at the end of the chamber. Utilizing the physical phenomenon of the Venturi effect, paint is drawn from a reservoir and atomized by the pressure gradient created by the accelerating air as it exits the spray gun nozzle via the aperture. 
         [0006]    Numerous factors affect the volume of liquid being ejected from conventional spray gun nozzles and the pattern at which it sprays, including the viscosity of the liquid, the cubic feet per minute (c.f.m.) of air being supplied by the compressor, the pressure at which that air is being regulated, regulation of the air by control valves in the spray gun itself, and modulation of the spray gun trigger by the user. Hence, while effective for quickly and efficiently covering a surface with paint, varnish, shellac, or similar liquid, the spray pattern of these devices can be difficult to control. Each parameter is independently adjustable with the result that adjusting the spray pattern is a complex, time consuming, and multi-handed procedure, entailing repeated trial and error. Too much liquid or too large a spray pattern results in overspray, damage to surrounding items, and wasted materials. Conversely, insufficient volumes of liquid or too small a spray pattern produces uneven coverage requiring repeated passes of the gun. In particular, the flow regulator of previously known devices requires two hands to operate, with the user grasping the device in one hand while the other is employed in manipulating the regulator control itself 
         [0007]    What is needed is a mechanism by which the spray pattern may be adjusted “on-the-fly.” Preferably, these adjustments may be carried out single-handedly. Additionally, the resulting spray pattern should be consistent and repeatable. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention is an improvement with regard to pneumatic paint sprayers, in particular including those utilizing high volume low pressure air sources, and including gravity fed as well as siphon type apparatuses. The improvement includes a thumb and/or finger adjustable mechanism for control of the trigger of the device whereby single-handed manipulation of a thumbscrew by the user controls the travel of the device trigger. Modulation of the trigger thereby allows the user to single handedly control the spray pattern produced by the apparatus in a consistent and repeatable manner. 
         [0009]    It is an object of the invention to provide an easily adjustable pneumatic spray gun; 
         [0010]    It is another object of the invention to provide a pneumatic spray gun with finger adjustable spray control; 
         [0011]    It is yet another object of the invention to provide a pneumatic spray gun that may be adjusted single-handedly, 
         [0012]    It is still another object of the invention to provide a pneumatic spray gun having a consistent, repeatable spray pattern; and, 
         [0013]    It is finally an object of the invention to provide a pneumatic spray gun with a trigger stop. 
         [0014]    The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a perspective view of an embodiment using a bottom mounted paint can; 
           [0016]      FIG. 2  is a perspective view of an embodiment using a top mounted paint can; 
           [0017]      FIG. 3  is a cutaway view of the embodiment shown in  FIG. 1 . 
           [0018]      FIG. 4  is a detailed elevation view of the thumbscrew adjustable trigger stop of the present invention; and, 
           [0019]      FIG. 5  is a front, three quarters perspective view of the thumbscrew adjustable trigger stop shown in  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    The preferred embodiments and best mode of the invention are shown in  FIGS. 1 through 5 . While the invention is described in connection with certain preferred embodiments, it is not intended that the present invention be so limited. On the contrary, it is intended to cover all alternatives, modifications, and equivalent arrangements as may be included within the spirit and scope of the invention as defined by the appended claims. 
         [0021]    This invention may be constructed from any suitable material including but not limited to appropriate metals, plastics and other polymers, ceramics, and combinations thereof. 
         [0022]    Turning to  FIGS. 1 and 2 , a spray gun with a bottom paint can mount  10  and a spray gun with a top paint can mount  20  are respectively shown. Both spray guns function identically with regard to the present invention and differ essentially only in the mechanism by which the liquid to be sprayed is delivered to the spraying assembly  15 ,  15 ′.  FIG. 1  depicts a siphon-style spray gun  10  with a paint can or reservoir  30  mounted below the spraying assembly  15  so that the liquid being sprayed is drawn into the spraying assembly  15  via a siphon tube  31  (see  FIG. 3 ) operated via the vacuum created by operation of the spraying assembly  15 .  FIG. 2  depicts a gravity-fed-style spray gun  20 , including a paint can or hopper  30 ′ mounted above the spraying assembly  15 ′. Instead of the siphon mechanism used with regard to the siphon-style device  10  of  FIG. 1 , an aperture (not shown) in the hopper  30 ′ allows the to-be-sprayed material to essentially drip into the spraying assembly  15 ′. Absent the improvements of the present invention, both apparatuses  10  and  20  operate in a conventional manner understood by those skilled in the art. 
         [0023]    In  FIG. 3 , the apparatus of the siphon-style spray gun  10  is shown in a cutaway view. Included is a reservoir  30  and siphon tube  31  used in a conventional manner to supply paint, varnish, or similar liquid to the spraying assembly  15 . The spraying assembly  15  operates in a generally conventional manner that will be understood by those skilled in the art and includes a fluid nozzle  52  in communication with the reservoir  30  and siphon tube  31 . An air nozzle  50  generally surrounds the fluid nozzle  52  such that a vacuum created by air entering the nozzle and thereafter being expelled from the spray aperture  56  tends to draw liquid up from the reservoir  30  via the siphon tube  31 . The liquid drawn through the siphon tube  31  subsequently mixes with and is atomized by the air from the air nozzle  50  with the result that the atomized paint, varnish, shellac, or similar liquid is ejected from the spray aperture  56  of the spraying assembly  15 . The amount of liquid being supplied to the spraying assembly  15  is controlled by a needle valve screw  80 . 
         [0024]    The pistol grip  17  of the inventive apparatus generally comprises the assembly for introduction of the compressed air or similar gas used for operation of the apparatus. An air inlet  40  is provided at the base of the pistol grip  17  whereby an air supply hose (not shown) may be attached in a conventional manner, for example using ¼ inch or ⅜ inch NPT (National Pipe Thread) fittings known to those skilled in the art. Gross adjustment of air pressure is regulated by an air adjustment screw  42  in communication with the air inlet  40  via an air channel  43  defined within the pistol grip  17 . Additionally, a secondary air adjustment screw  54  is provided in the upper body portion of the spray gun  10 . A plunger valve  44  impinging on the air channel  43  facilitates infinitely adjustable control of the air supplied to the apparatus  10  whereby reciprocal manipulation by the operator of the trigger  46  rotating about its trigger pivot  48  and engaging the plunger valve  44  causes air to enter the spraying assembly  15  as described above with the result that atomized liquid is ejected from the spraying assembly  15 . 
         [0025]    The novel finger adjustment wheel  86  of the present invention  10  and its accessory components are most clearly shown in  FIGS. 3 through 5 . Specifically, a needle valve sleeve  82  is slidably mounted coaxially about the needle valve screw  80  and threadably fixed within the pistol grip  17  such that the distal portion of the sleeve  82  comprising a needle valve sleeve shoulder  84  functions as a trigger stop whereby it engages and thereby limits the movement of the trigger  46 . As clearly shown in  FIGS. 3 through 5 , the finger adjustment wheel  86  is mounted in the pistol grip  17  such that it can easily be accessed by the user with the same hand gripping the apparatus  10  of the present invention. The wheel  86  is in communication with the needle valve sleeve  82  such that rotation of the wheel  86  and resulting axial rotation of the needle valve sleeve causes longitudinal, reciprocal movement of the needle valve sleeve shoulder  84  pursuant the longitudinal translation of rotational motion by the threaded proximal portion  88  of the needle valve sleeve. As shown in detail in  FIGS. 4 and 5 , the trigger  46  includes a trigger aperture  47  sized to allow unimpeded passage of the needle valve screw  80  but sized such that the travel of trigger  46  is limited by the position of the needle valve sleeve shoulder  84 . Therefore, in use, manipulation of the finger adjustment wheel  86  causes reciprocal movement of the needle valve sleeve shoulder  84  to limit movement of the trigger  46  such that the spray pattern is not dependant on the user&#39;s ability to modulate the position of the trigger  46 . Rather, the user can simply pull the trigger  46  until it bears on the needle valve sleeve shoulder  84  with the result that the spray pattern of the device  10  may be controlled by the finger adjustment wheel  86  resulting in easily repeatable and consistent spray patterns. 
         [0026]    The principles, preferred embodiments and modes of operation of the present invention have been described in the foregoing specification. However, the invention should not be construed as limited to the particular embodiments which have been described above. Instead, the embodiments described here should be regarded as illustrative rather than restrictive. Variations and changes may be made by others without departing from the scope of the present invention as defined by the following claims: