ELECTROSTATIC SPRAY GUN

• US 3,819,115 A
• Filed: 03/12/1973
• Issued: 06/25/1974
• Est. Priority Date: 03/13/1972
• Status: Expired due to Term

• Current Assignee: Claes Erik Soderman
• Original Assignee: Claes Erik Soderman
• Inventors: Soderman, Claes Erik
• Primary Examiner(s): Wood, Jr., M. Henson
• Assistant Examiner(s): Mar, Michael Y.
• Application Number:
  US05/340,549
• Time in Patent Office: 470 Days
• Field of Search: 239/15,3 317/2R,3,4
• US Class Current: 239/698
• CPC Class Codes: B05B 5/032 for spraying particulate materials

Abstract

The powder spray gun comprises a handle, a barrel and a front member screwed to the barrel. The barrel and the front member form a duct through which paint powder is conveyed entrained in the air. An annular electrode and an elongated central body are clamped between the barrel and the front member and a lead for high voltage extends through an axial bore in the barrel and abuts axially against the annular electrode. The duct is annular and the electrode has an annular forward-directed edge that has a clearance to the walls of the duct and is located at a touch protecting distance from the mouth of the duct.

Claims

1. A powder spray gun having:

an annular powder emitting duct having a mouth at the forward end thereof for emitting said powder, the outer and inner walls of which are formed of an electrically insulating material, to which duct the powder is to be carried suspended in a gas, and an electrode connectable to a source of high voltage, said electrode comprising an annular base secured to the outer wall of the duct and means extending from said annular base and forming an annular forwardly directed edge portion which has a radial clearance to the walls of the duct and is recessed in said duct at a touch-protecting distance from the mouth of the duct, said forwardly directed edge portion being the foremost extending portion of the electrode in the duct.

2. A powder spray gun as defined in claim 1 in which said edge portion is a circular continuous edge.

3. A powder spray gun as defined in claim 1 in which said extending means comprises a plurality of needles having forwardly directed tips forming together a discontinuous annular forwardly directed edge.

4. A powder spray gun as defined in claim 1 including means located rearwardly of said electrode for imparting a twisting motion to the powder suspeNsion transmitted through the duct.

5. A powder spray gun as defined in claim 1 in which said electrode is axially clamped between a rear body and a forward body which form together the outer wall of said duct.

6. A powder spray gun as defined in claim 5 in which said forward and rear bodies are screwed together.

7. A powder spray gun as defined in claim 5 in which an elongated central body, forming the inner wall of the duct, has a mount which is axially clamped, together with said annular base of the electrode, between said rear and forward bodies forming the outer wall of the duct.

8. A powder spray gun as defined in claim 7 in which said elongated body at its rear end has radial fins for imparting a twisting motion to the powder suspension transmitted through the duct.

9. A powder spray gun as defined in claim 7 in which said elongated body carries a deflector disposed outside of the mouth of the duct.

10. A powder spray gun as defined in claim 5 in which a lead connected to high voltage is located in an axial passage in said rear body and abuts axially against the electrode to apply high voltage thereto.

11. A powder spray gun comprising:

a front and a rear member made of an electrically insulating material and forming a wall of a powder emitting duct, the rear end of said duct being adapted to receive a flow of powder entrained in air, an annular electrode clamped between said front and rear members, said electrode having a forwardly directed extension comprised of a plurality of forwardly directed needle-shaped elements in said duct, said forwardly directed extension having a clearance to the wall of the duct, and a lead for high voltage located in an axial passage in said rear member and abutting axially against the electrode to apply high voltage thereto.

12. A powder spray gun comprising:

a barrel of electrically insulating material, an axial duct in said barrel adapted to be supplied with a flow of powder suspended in a carrier gas, a cap of electrically insulating material removably attached to said barrel, said cap having a duct forming an extension of said axial duct in the barrel and forming a powder emitting mouth, an annular electrode connectable to a source of high voltage and having a forwardly directed edge portion which has a radial clearance to the duct of said cap and is recessed in said duct at a touch protecting distance from said mouth, said forwardly directed edge portion being the foremost extending portion of the electrode in the duct, and a device upstream of said electrode to impart a twisting motion to the powder-gas suspension transmitted through the duct, said device and said electrode being fastened in the duct by being axially clamped between said barrel and said cap.

13. A powder spray gun as defined in claim 12 in which said device is formed of electrically insulating material and has an extension that extends forwardly through the annular electrode to said mouth of the duct.

14. A powder spray gun as defined in claim 12 in which said device is formed of electrically insulating material and comprises a body coaxially located in the duct and carried by spokes, said body exending forwardly through said electrode and said mouth, a gas passage leading through one of said spokes and through said central body to provide for a deflecting gas flow substantially transverse to the flow of powder and gas emitted from said mouth, said gas passage being connected to a gas supply passage in said barrel.

15. A powder spray gun as defined in claim 12 in which said edge portion is a circular continuous edge.

16. A powder spray gun as defined in claim 12 in which said extending means comprises a plurality of needles having forwardly directed tips forming together a discontinuous annular forwardly directed edge.

17. A powder spray gun having:

an annular duct defined by an outer and an inner wall of electrically insulating material, said duct forming a powder emittIng mouth and being adapted to be supplied with a flow of powder suspended in a carrier gas, a plurality of forwardly directed electrode points located annularly in the annular duct and recessed in the duct at a given distance from said mouth, and means for connecting said electrode points to a source of high voltage.