Patent Application
20130075489
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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. The apparatus includes a built-in gas pressure gauge and adjustable controls for modulating the spray characteristics of the paint, stain or similar liquid being ejected therefrom.
Spray guns, especially those used with spray painting apparatuses, atomize the liquid paint by means of compressed air, generally provided via an air compressor, which enters a nozzle area via a chamber surrounding a fluid nozzle. This 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 pressurized 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, the length and diameter of the air hose connecting the compressor and spray gun, 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.
Modern paints require precise control of air pressure in order to coat uniformly and hence the air pressure provided by the compressor and the consistency of same are particularly important. Accordingly, compressors generally include pressure regulators and pressure gauges so that the pressure at the junction of the compressor outlet and hose inlet may be monitored. However, because the length and diameter of the hose connecting the compressor affect the pressure actually delivered at the spray gun air inlet, the pressure reading indicated at the compressor regulator can differ significantly from that actually being delivered at the spray gun. Elaborate charts and diagrams are available which take into account variables such as the air hose length and diameter thereby allowing a user to estimate the delivery pressure. Additionally, accessory pressure gauges have been developed for installation between the air hose outlet and the inlet of the spray gun. However, the aforementioned charts are only able to provide estimates of the actual pressure being delivered and inline pressure gauges do not indicate the pressure actually being delivered at the spray gun nozzle. What is needed therefore is an indication of the air pressure actually being supplied at the spray gun nozzle.
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 gas pressure gauge built into the paint sprayer in communication with the paint sprayer gas passages. The user is thereby able to monitor and control the air pressure as close to the nozzle of the paint sprayer as possible and optimizing the delivery of the material being sprayed.
It is an object of the invention to provide a spray gun having a built-in pressure gauge;
It is another object of the invention to provide a pneumatic spray gun with a pressure gauge that accurately indicates the pressure at which material is being sprayed;
It is yet another object of the invention to provide a pneumatic spray that facilitates monitoring of fluctuations in air pressure; and,
It is finally an object of the invention to provide a pneumatic spray gun that facilitates optimal delivery of the material being sprayed.
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 modes 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.
In
As shown in
The pistol grip 17 of the inventive apparatus 10 generally holds the assembly for introduction of the compressed air or similar gas used for operation of the apparatus 10. An air inlet 40 is formed at the base of the pistol grip 17 allowing an air supply hose (not shown) to 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 portion of the pistol grip 17. A plunger valve 44 impinging on the air channel 43 facilitates infinitely adjustable control of the air supplied to the apparatus 10 whereby fore and all manipulation by the operator of the trigger 46 rotating about its trigger pivot 48 and bearing on 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.
A gas pressure gauge 86 is mounted in the upper portion of the pistol grip 17. In a preferred embodiment, the gas pressure gauge 86 is a digital gas pressure gauge 86 and includes a battery 87 in electrical communication therewith. The battery 87 is housed in a chamber defined in the spray gun housing. One skilled in the art will understand, however, that pressure gauges are well known and include force collector type sensors, for example, piezoresistive strain gauge, capacitive, electromagnetic, piezoelectric, optical, and potentiometric sensors, as well as electronic pressure sensors utilizing other phenomena, for example, resonant, thermal, ionization sensors, and the like. All are contemplated herein. The gas pressure gauge 86 is in gaseous communication with air channel 43 such that gas pressure is sampled essentially adjacent the air nozzle 50 of the spraying assembly 15. In a preferred embodiment the gas pressure gauge 86 further includes a digital display 90, 90′ (see
In a preferred embodiment, the gas pressure gauge 86 and digital display 90, 90′ are able to accommodate pressure readings up to and including 2 bar (approximately 29 lbs/in2 (i.e., p.s.i.)). Larger and smaller maximum pressure readings are also contemplated.
In use, the proximity of the gas pressure gauge 86 of the apparatus of the present invention ensures accurate and convenient monitoring and control of the actual gas pressure at the point at which material is being ejected from a pneumatic paint and/or liquid sprayer.
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:
