Induction spray charging apparatus

An air-assisted airless spray apparatus comprising:

• a spray gun;
• at least a first air passageway in said gun for delivering air at high volume and low pressure;
• at least a first liquid passageway in said gun for delivering liquid to be sprayed at a high pressure;
• an air cap mounted on said spray gun for rotation with respect to said spray gun;
• an air orifice centrally located in said cap;
• a second air passageway in said cap for engaging said first air passageway and for delivering said air through said air orifice to produce a low pressure, low turbulence air flow along a flow path;
• a high pressure airless nozzle connected to said first liquid passageway for receiving said liquid to be sprayed and having a forward end extending into said second air passageway;
• a spray tip at said nozzle forward end having an outlet orifice for discharging a spray of liquid from said nozzle liquid passageway along said flow path and within said air flow, whereby said air flow provides a low turbulence air envelope around said liquid spray;
• a flow control needle valve movable within said nozzle to control the flow of liquid to said liquid outlet orifice, thereby to control the discharge of said liquid;
• at least one electrode adjacent said liquid outlet orifice and said flow path;
• and
• a voltage source connected to said electrode, said voltage having a first polarity and being sufficiently high to produce an electric field in said flow path which will induce charges having a second polarity on said liquid spray.

An air-assisted airless spray apparatus comprising:

• a spray gun;
• at least a first air passageway in said gun for delivering air at high volume and low pressure;
• at least a first liquid passageway in said gun for delivering liquid to be sprayed at a high pressure;
• an air cap mounted on said spray bun for rotation with respect to said spray gun;
• an air orifice centrally located in said cap;
• a second air passageway in said cap for engaging said first air passageway and for delivering said air to said first air orifice;
• a high pressure airless nozzle connected to said first liquid passageway for receiving liquid and having a forward end extending into said second air passageway;
• a spray tip at said nozzle forward end having an outlet orifice for discharging a liquid spray from said nozzle liquid passageway along a flow path;
• a flow control needle valve movable within said nozzle to control the flow of liquid to said liquid outlet orifice, thereby to control the discharge of said liquid;
• an electrode adjacent and concentric with said liquid outlet orifice and said flow path;
• a voltage source connected to said electrode, said voltage having a first polarity and being sufficiently high to produce an electric field in said flow path which will induce charges having a second polarity on said liquid spray, and being insufficient to produce gaseous ionization;
• and
• a rotatable electrical connector between said spray gun and said cap for maintaining an electrical connection therebetween at any rotational angle of said cap to thereby connect said voltage source to said electrode.

Spray gun apparatus comprising:

• a spray gun liquid nozzle having an orifice;
• an induction air cap body portion having a front face, a rear face, and an outer surface therebetween;
• an axial opening extending through said cap body portion for receiving said spray gun nozzle;
• means directing liquid to be sprayed through said nozzle orifice;
• means directing atomizing air through said axial opening around said spray gun liquid nozzle;
• at least one curved electrode support on said cap front face adjacent said nozzle orifice, said electrode support having an inner surface spaced radially from said orifice;
• electrode means on said electrode support inner surface;
• a rotatable connector having a first component on said air cap body portion for engaging a corresponding second rotatable connector component on said spray gun for providing a rotatable electrical connection between a power supply and said air cap body;
• means including a control resistance electrically connecting said power supply through said rotatable connector to said electrode means for supplying a charging voltage to said electrode means, whereby charges are induced on sprayed liquid from said spray nozzle.