Itw Limited

The Devilbiss Company

Bate, Anthony J.

Whitby, David P.

Smith, Rowland C.

Anthony J Bate

Rowland C Smith

Neville Thomas Pettit

David P Whitby

Andrew Edge

Tony Heard

Spray gun

Air valve

Indexing air cap

A spray gun operable by low pressure high volume air is described. The spray gun (10) comprises an air cap (128) formed with a central spraying aperture and a fluid nozzle (70) projecting toward the spraying aperture, the profile of the nozzle is a plain frustum of a core terminating at a small front face bounding an orifice through which fluid is discharged. The arrangement being such that in operation a flow of atomizing air that emerges through a gap between the nozzle (70) and the air cap (128) attaches to the nozzle (70) and to an emergent fluid jet which assumes a conical form that is a continuation of the nozzle surface and changes to a parallel jet before it breaks up into atomized droplets.

An external mix miniature spray gun of the airbrush type obtains a spray of paint by directing a jet of gas from a source over a nozzle. A reducing valve for the flow of gas is connected at one end to the source and to an outlet at the other end for discharge into the body of the gun. The reducing valve includes a body of circular end profile with the inlet leading to first generally radial flow passages opening to the side of the valve body and second generally radial flow passages leading from the side of the valve body to the outlet. A sleeve is rotatably retained on the valve body by interengaging threads and spans between the first and second radial passages to define an internal space for gas flow therebetween. A tapered surface in the gas flow space on the interior of the sleeve is arranged to approach or withdraw from a portion of the valve body to enlarge or diminish the gap therebetween as the sleeve is rotated relative to the body. At small degrees of valve opening the second radial passages are masked by the threads of the sleeve so that the threads provide a flow resistance facilitating control at low gas flow rates. With such a valve the flow of air through the airbrush can be shut off in the airbrush itself rather than at the source, the pressure can be adjusted in accordance with the fluid being sprayed, and if the source is an aerosol type bottle the pressure can be regulated to maximize the aerosol life.

Miniature spray guns

Growing community of inventors

Bournemouth, United Kingdom

Anthony J Bate