SPRAY CHARGING DEVICE

• US 3,698,635 A
• Filed: 02/22/1971
• Issued: 10/17/1972
• Est. Priority Date: 02/22/1971
• Status: Expired due to Term

• Current Assignee: James E. Sickles
• Original Assignee: James E. Sickles
• Inventors: Sickles, James E.
• Primary Examiner(s): Wood, Jr., M. Henson
• Assistant Examiner(s): Grant, Edwin D.
• Application Number:
  US05/117,494
• Time in Patent Office: 603 Days
• Field of Search: 239/3,15 317/3 117/17,93.4 118/621
• US Class Current: 239/3
• CPC Class Codes: B05B 5/03 characterised by the use of gas , e.g. electrostatically assisted pneumatic spraying B05B5/04, B05B5/043, B05B5/047 take precedence
• CPC Class Codes: B05B 5/043 using induction-charging

Abstract

An electrostatic spray charging device wherein means in a passageway or a barrel of such device directs a jet of air between a charged electrode in the passageway and a plurality of liquid termini at an orifice within the passageway in a manner as to direct particles atomized from the plurality of termini generally away from the charged electrode and the side walls of the passageway. The charged electrode and the liquid termini are adapted to be connected to an electrical source thereby creating a potential difference between the charged electrode and the liquid termini. The potential difference therebetween provides a high intensity electric field at the liquid termini whereby particles atomized from the individual liquid termini carry a high charge-to-mass ratio. Preferably, the jet of air passing between the charged electrode and the liquid termini assists in atomizing liquid particles from the liquid termini. The charged liquid particles are attracted to and deposited upon the surface of an object or article at a particle attracting potential.

Claims

1. A low voltage electrostatic spray gun comprising a barrel including a passageway terminating in an opening, the barrel including dielectric means for forming liquid into a stream, the stream having a plurality of termini in the passageway and spaced rearwardly from the opening, the liquid termini providing liquid particles, electrode means confined within the passageway rearwardly of the opening and in close proximity with the liquid termini, the electrode means and the stream of liquid adapted to be connected to means for creating a potential difference between the electrode means and the liquid termini, the potential difference therebetween providing an electric field having a high potential gradient at the termini, the dielectric means assisting in concentrating the electric field at the liquid termini so as to electrostatically charge the liquid particles, and means in the barrel for directing a jet of air along the passageway to carry the charged liquid particles formed from the liquid termini away from the side walls of the passageway and the electrode means.

2. The low voltage electrostatic spray gun of claim 1, wherein the jet of air assists in atomizing particles from the liquid termini.

3. The low voltage spray gun of claim 1, wherein the dielectric means forms the liquid into a stream having an axis that is substantially parallel to the axis of the electrode means.

4. The low voltage device of claim 1 wherein the dielectric means for forming the stream includes a tube and a cap spaced from the open end of the tube to provide an orifice from which the stream of liquid is emitted at an angle to the electrode, the cap having a radial extent slightly greater than the radial extent of the tube.

5. The low voltage device of claim 4, wherein the portion of the passageway in front and extending away from the cap has an expanding volume.

6. The low voltage spray gun of claim 1, wherein the electrode means is annular and the dielectric means forms the liquid into a stream having an axis substantially concentric with the axis of the annular electrode.

7. A low voltage electrostatic spray device comprising a barrel having an opening, a passageway in the barrel terminating in an opening near the opening of the barrel, means in the barrel providing a liquid stream having termini from which liquid particles are formed in the passageway rearwardly of the opening of the passageway, the means providing the stream includes a cap spaced from an open end of a tube to form an orifice from which the stream of liquid is emitted, the cap having a radial extent different from the radial extent of the tube, electrode means in the passageway and rearwardly of the opening of the passageway and in close proximity to the liquid termini, means connected to the electrode means and the liquid stream to establish an electric field having a high gradient at the termini of the liquid, the electric field being concentrated at the liquid termini, and means directing a jet of air along the passageway between the electrode means and the liquid termini for projecting electrostatically charged liquid particles generally away from the side walls of the passageway and out of the opening of the passageway and the opening of the barrel.

8. A low voltage electrostatic device as claimed in claim 7, wherein the means providing the liquid stream is fabricated from dielectric material to assist in concentrating the electric field at the liquid termini.

9. A low voltage electrostatic device as claimed in claim 8, wherein the voltage applied to the electrode means is of such a value to prevent corona discharge.

10. A method of forming a cloud of electrostatically charged liquid coating material particles comprising the steps of providing A liquid stream of coating material having a plurality of liquid termini in a passageway and spaced rearwardly from an end of the passageway, creating a potential difference between an electrode means in the passageway and spaced rearwardly from the opening and the liquid termini, the potential difference therebetween providing an electric field having a high potential gradient at the liquid termini, forming charged liquid particles from the liquid termini having a polarity different from the polarity of the electrode means, and directing a jet of air along the passageway to carry the charged liquid coating material particles formed from the liquid termini away from the side walls of the passageway to form a cloud of electrostatically charged liquid particles.

11. The method of claim 10, wherein the liquid is paint having a resistivity of about 15 megohm-centimeters or less.

12. The method of claim 10, wherein the stream having a plurality of liquid termini is formed on a dielectric means.

13. The low voltage device of claim 1, wherein the dielectric means for forming the stream includes a tube and a cap spaced from the open end of the tube to provide an orifice from which the stream of liquid is emitted.

14. The low voltage device of claim 13, wherein the cap has a radial extent different from the radial extent of the tube.

15. A low voltage electrostatic spray gun comprising a barrel having an opening, a passageway in the barrel terminating in an opening near the opening of the barrel, the barrel including dielectric means for forming liquid into a stream, the stream having a plurality of termini in the passageway and spaced rearwardly from the opening of the passageway, the liquid termini providing liquid particles, electrode means confined within the passageway rearwardly of the opening of the passageway and in close proximity with the liquid termini, the electrode means and the stream of liquid adapted to be connected to means for creating a potential difference between the electrode means and the liquid termini, the potential difference therebetween providing an electric field having a high potential gradient at the termini, the dielectric means assisting in concentrating the electric field at the liquid termini so as to electrostatically charge the liquid particles, and means in the barrel for directing a jet of air along the passageway to carry the charged liquid particles formed from the liquid termini away from the side walls of the passageway and electrode means and out of the opening of the passageway and the opening of the barrel.