Spray apparatus with atomization device

Claim 2

In an electrostatic spray system, the combination comprising: a spray head for issuing intersecting streams of material and air to produce an atomized spray of material particles including an electrically conductive centrally disposed material dispensing nozzle having an orifice passage along an axis thereof for discharging the material and a plane concentric surface formed at the external end of the orifice passage at right angle to said axis for receiving said discharging material as a thin sheet of said material, as said material flows to the outer edge of said plane surface, and a non-electrically conductive means in surrounding relation to said centrally disposed nozzle in a generally circular pattern there-around to form a concentric air passage with said nozzle for issuing a moving shroud of air which atomizes said sheet of material as it flows to the outer edge of said circular plane concentric surface; means for supplying air under pressure to the spray head; means for supplying material under pressure to the spray head; means, including an emitter electrode disposed in the path of the particle spray in downstream spaced relation to the spray head, for establishing a rearwardly directed corona discharge terminating at the electrically conductive nozzle of the spray head to charge the coating material particles electrostatically; a high voltage power supply for energizing the emitter electrode; and means for preventing sparking between the emitter electrode and the spray head nozzle, the spark preventing means including switch means disposed within the spray gun and responsive to the flow of shroud air to the spray head for electrically connecting the high voltage power supply to the emitter electrode to establish the corona discharge, whereby air flows from the spray head and over the emitter electrodE prior to the initiation of the corona discharge, said flow of air being effective to prevent sparking between the emitter electrode and the spray head in the absence of the particle spray.

Claim 3

An electrostatic spray system according to claim 1 further comprising: means defining at least one passage within the spray gun for conducting air to the spray head, the switch means being located in communication with the air passage and being responsive to the flow of air through the passage to connect the high voltage power supply electrically to the emitter electrode.

Claim 4

An electrostatic spray system according to claim 2 further comprising: individually operable valves in the spray gun for controlling the flow of coating material and air from the spray head, and operator means associated with the spray gun for sequentially opening the air and coating material valves, the operator means being arranged to open the air valve prior to opening the coating material valve so that the air is delivered to and discharged from the spray head, and the air flow-responsive switch is actuated to energize the emitter electrode, before coating material is issued from the spray head.

Claim 5

An electrostatic spray apparatus for spraying a liquid coating material, the combination comprising: a body provided with a passage having an intake for connection to a source of liquid coating material, said passage having an outlet; a nozzle assembly including a nozzle secured to said body at said outlet through which liquid coating material can be discharged into atmosphere, said nozzle having an external plane surface having peripherical edge with an aperture therein forming a discharge orifice for the coating material; means for forming a layer of liquid coating material on said external plane surface of said nozzle upon passage through said discharge orifice of said nozzle; an electrical insulation member encompassing said nozzle and forming a continuous opening surrounding the peripherical edge of the plane surface of said nozzle, through which an air stream is passed, causing said layer of liquid coating material to flow over the external plane surface of said nozzle and for atomizing said layer of coating material into finely divided particles to be discharged from the apparatus; at least one metallic charging electrode secured to said body, said charging electrode having a sharp point, extending rearwardly toward said nozzle and terminating adjacent thereto; and means for imposing a high electrical potential between said charging electrode and said nozzle to generate an electrical corona discharge therebetween in which the principal component is in a rearward direction and terminates at said nozzle in the vicinity of said outlet, whereby the discharged particles from the apparatus acquire an electrical charge along a path, the direction of which is opposite to that of components of the corona discharge.

Claim 6

An electrostatic spray apparatus for spraying a liquid coating material, the combination comprising: a body provided with a passage having an intake for connection to a source of liquid coating material, said passage having an outlet; a nozzle assembly including a nozzle secured to said body at said outlet through which liquid coating material can be discharged into atmosphere, said nozzle having an external plane surface having peripherical edge with an aperture therein forming a discharge orifice for the coating material; means for forming a layer of liquid coating material on said external plane surface of said nozzle upon passage through said discharge orifice of said nozzle; an electrical insulation member encompassing said nozzle and forming a continuous opening surrounding the peripherical edge of the plane surface of said nozzle, through which an air stream is passed, causing said layer of liquid coating material to flow over the external plane surface of said nozzle and for atomizing said layer of coating material into finely divided particles to be discharged from the apparatus; at least one metallic charging electrode secured to said body, said charging electrode having a sharp point, extending rearwardly toward said nozzle and terminating adjacent thereto; and means for imposing a high electrical potential between said charging electrode and said nozzle to generate an electrical corona discharge therebetween in which the principal component is in a rearward direction and terminates at said nozzle in the vicinity of said outlet, whereby the discharged particles from the apparatus acquire an electrical charge along a path, the direction of which is opposite to that of components of the corona discharge.

Claim 7

An electrostatic spray gun of the type in which a spray of coating material particles is produced by interacting streams of coating material and air under pressure comprising: a. a spray head for issuing intersecting streams of material and air to produce an atomized spray of material particles including an electrically conductive centrally disposed material dispensing nozzle having an orifice passage along an axis thereof for discharging the material and a plane concentric surface formed at the external end of the orifice passage at right angle to said axis for receiving said discharging material as a thin sheet of said material, as said material flows to the outer edge of said plane surface, and a non-electrically conductive means in surrounding relation to said centrally disposed nozzle in a generally circular pattern there-around to form a concentric air passage with said nozzle for issuing a moving shroud of air which atomizes said sheet of material as it flows to the outer edge of said circular plane concentric surface, b. means for supplying air under pressure to the sPray head, c. means for supplying material under pressure to the spray head, d. means, including an emitter electrode disposed in the path of the particle spray in downstream spaced relation to the spray head, for establishing a rearwardly directed corona discharge terminating at the spray head to charge the coating material particles electrostatically, e. means for preventing sparking between the emitter electrode and the nozzle of the spray head, the spark-preventing means including switch means responsive to the flow of air to the spray head for energizing the emitter electrode, whereby air flows from the spray head and over the emitter electrode prior to the initiation of the corona discharge, said flow of air being effective to prevent sparking between the emitter electrode and the spray head in the absence of the particle spray, and f. means defining at least one passage within the gun for conducting air to the spray head, the switch means being located within the gun in communication with the air passage to the spray head.

Claim 8

An electrostatic spray gun of the type in which a spray of coating material particles is produced by interacting streams of coating material and air under pressure comprising: a. a spray head for issuing intersecting streams of material and air to produce an atomized spray of material particles including an electrically conductive centrally disposed material dispensing nozzle having an orifice passage along an axis thereof for discharging the material and a plane concentric surface formed at the external end of the orifice passage at right angle to said axis for receiving said discharging material as a thin sheet of said material, as said material flows to the outer edge of said plane surface, and a non-electrically conductive means in surrounding relation to said centrally disposed nozzle in a generally circular pattern there-around to form a concentric air passage with said nozzle for issuing a moving shroud of air which atomizes said sheet of material as it flows to the outer edge of said circular plane concentric surface, b. means for supplying air under pressure to the sPray head, c. means for supplying material under pressure to the spray head, d. means, including an emitter electrode disposed in the path of the particle spray in downstream spaced relation to the spray head, for establishing a rearwardly directed corona discharge terminating at the spray head to charge the coating material particles electrostatically, e. means for preventing sparking between the emitter electrode and the nozzle of the spray head, the spark-preventing means including switch means responsive to the flow of air to the spray head for energizing the emitter electrode, whereby air flows from the spray head and over the emitter electrode prior to the initiation of the corona discharge, said flow of air being effective to prevent sparking between the emitter electrode and the spray head in the absence of the particle spray, and f. means defining at least one passage within the gun for conducting air to the spray head, the switch means being located within the gun in communication with the air passage to the spray head.

Claim 9

An electrostatic spray gun of the type in which a spray of coating material particles is produced by interacting streams of coating material and air under pressure comprising: a. a spray head for issuing intersecting streams of material and air to produce an atomized spray of material particles including an electrically conductive centrally disposed material dispensing nozzle having an orifice passage along an axis thereof for discharging the material and a plane concentric surface formed at the external end of the orifice passage at right angle to said axis for receiving said discharging material as a thin sheet of said material, as said material flows to the outer edge of said plane surface, and a non-electrically conductive means in surrounding relation to said centrally disposed nozzle in a generally circular pattern there-around to form a concentric air passage with said nozzle for issuing a moving shroud of air which atomizes said sheet of material as it flows to the outer edge of said circular plane concentric surface, b. means for supplying air under pressure to the spray head, c. means for supplying material under pressure to the spray head, and d. means, including an emitter electrode disposed in the path of the particle spray in downstream spaced relation to the spray head, for establishing a rearwardly directed corona discharge terminating at the spray head to charge the coating material particles electrostatically, said emitter electrode being supported on the spray head assembly and extending transversely into the spray and thereafter curving rearwardly to terminate at a point in front of the spray material orifice, and the said moving shroud of discharge air being inclined with respect to the axis of the spray material orifice to an extent that the air exiting from the spray head converges toward the rearwardly extending portion of the electrode.

Claim 10

An electrostatic spray gun of the type in which a spray of coating material particles is produced by interacting streams of coating material and air under pressure comprising: a. a spray head for issuing intersecting streams of material and air to produce an atomized spray of material particles including an electrically conductive centrally disposed material dispensing nozzle having an orifice passage along an axis thereof for discharging the material and a plane concentric surface formed at the external end of the orifice passage at right angle to said axis for receiving said discharging material as a thin sheet of said material, as said material flows to the outer edge of said plane surface, and a non-electrically conductive means in surrounding relation to said centrally disposed nozzle in a generally circular pattern there-around to form a concentric air passage with said nozzle for issuing a moving shroud of air which atomizes said sheet of material as it flows to the outer edge of said circular plane concentric surface, b. means for supplying air under pressure to the spray head, c. means for supplying material under pressure to the spray head, and d. means, including an emitter electrode disposed in the path of the particle spray in downstream spaced relation to the spray head, for establishing a rearwardly directed corona discharge terminating at the spray head to charge the coating material particles electrostatically, said emitter electrode being supported on the spray head assembly and extending transversely into the spray and thereafter curving rearwardly to terminate at a point in front of the spray material orifice, and the said moving shroud of discharge air being inclined with respect to the axis of the spray material orifice to an extent that the air exiting from the spray head converges toward the rearwardly extending portion of the electrode.

Claim 11

A spray gun according to claim 6 in which the rearwardly directed corona discharge terminating at the spray head is confined between the electrically conductive centrally disposed fluid nozzle and the rearwardly curved emitter electrode tip and to the plane concentric surface formed at the external end of the orifice passage along the axis thereof.