Patent Application
20120292411
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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.
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.
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
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.
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.
It is an object of the invention to provide an easily adjustable pneumatic spray gun;
It is another object of the invention to provide a pneumatic spray gun with finger adjustable spray control;
It is yet another object of the invention to provide a pneumatic spray gun that may be adjusted single-handedly,
It is still another object of the invention to provide a pneumatic spray gun having a consistent, repeatable spray pattern; and,
It is finally an object of the invention to provide a pneumatic spray gun with a trigger stop.
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.
The preferred embodiments and best mode of the invention are shown in
This invention may be constructed from any suitable material including but not limited to appropriate metals, plastics and other polymers, ceramics, and combinations thereof.
Turning to
In
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.
The novel finger adjustment wheel 86 of the present invention 10 and its accessory components are most clearly shown in
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:
