US 4,241,880 A · Electrostatic spray gun

Abstract

An improved electrostatic spray gun is disclosed including an electrically conductive metal handle assembly, an electrically insulative barrel assembly, and an electrically insulative nozzle assembly terminating at its forward end in a small diameter discharge orifice through which the coating material is ejected. An ionizing electrode protrudes from the discharge orifice. The flow of material through the barrel and the nozzle assembly is controlled by a trigger actuated needle and seat valve assembly close to the discharge orifice and in axial alignment with an annular fluid flow passageway in the barrel portion of the gun. A high value resistor is disposed in the barrel portion of the gun and a second lower value resistor is disposed inside the needle valve immediately upstream of the ionizing electrode. The elements of the improved electrostatic spray gun cooperate to provide clean and safe operation.

Claims11

Dependent claims

An electrostatic coating apparatus comprising:

a nozzle made from a substantially nonconductive material having a coating material passageway in it terminating at one end in a material discharge orifice through which coating material is ejected,
a charging electrode protruding from said nozzle orifice,
a needle and seat valve in said nozzle passageway operative to selectively open and close said nozzle orifice,
a high voltage electrical path passing through said valve adapted to connect said charging electrode to a source of high voltage electrical power, and
a least a first series resistor in said needle in said electrical path.

2 more elements

An electrostatic spray gun coating apparatus comprising:

a barrel portion having a coating material conduit and a high voltage electrical path therein, said path having a first and second end, said first end of said electrical path being adapted to be connected to a source of high voltage electrical power,
a nozzle portion made of substantially nonconductive material connected to the forward end of said barrel portion and having a generally axial coating material passageway therethrough substantially axially aligned with said coating material conduit in said barrel, said passageway in said nozzle terminating at its forward end in a material discharge orifice through which coating material is ejected,
valve means in said nozzle comprising a control rod axially slidably movable in said conduit in said barrel and in said passageway in said nozzle and a coned seat formed inside said nozzle close to said discharge orifice, said control rod being formed of an electrically nonconductive material and terminating at its forward end in a coned tip adapted to mate with said seat for controlling the flow of coating material through said discharge orifice,
a charging electrode mounted at one end in said forward end of said control rod and protruding from said nozzle orifice,
a high voltage electrical path passing through at least the forward end of said control rod,
a first series resistor mounted in said forward end of said control rod in said electrical path passing therethrough, said first series resistor being connected at its forward end to said charging electrode, and
means for electrically connecting the other end of said resistor to said second end of said electrical path in said barrel to thereby connect said charging electrode to said source of high voltage electrical power while permitting axial movement of said control rod.

4 more elements

Dependencies are inferred from the claim text.

Electrostatic spray gun

Life of this patent

Electrostatic spray gun

Life of this patent

Abstract

Claims11