Electrostatic spraying apparatus

Claim 2

Electrostatic spraying apparatus including a spray nozzle and a high-voltage generator, said generator comprising a passage for transporting a gaseous fluid to said spray nozzle, said passage having a convergent-divergent portion for imparting a supersonic speed to at least part of said gaseous fluid, and electrode means adjacent said convergent-divergent portion for transmitting electric charges to said gaseous fluid.

Claim 3

Apparatus according to claim 1, including means for injecting solid particles into the passage upstream of the the electrode means.

Claim 4

Apparatus according to claim 2, including means for injecting a volatile liquid into said passage upstream of the electrode means.

Claim 5

Apparatus according to clAim 1, wherein the outlet of the passage for the gaseous fluid transporting the electric charges is adjacent to the outlet of said spray nozzle, in a position such that the gaseous fluid contributes to the atomization of a liquid sprayed out of the nozzle.

Claim 6

Apparatus according to claim 1, including means for injecting particles of a product to be sprayed close to the electrode means.

Claim 7

Apparatus according to claim 1, including a chamber into which a passage transporting the product to be sprayed discharges, as well as the passage for the gas transporting the electric charges, and a further passage leading from said chamber towards said spray nozzle.

Claim 8

Apparatus according to claim 1, wherein the nozzle is made of an insulating material and the passage for the gas transporting the electric charges discharges into the atmosphere adjacent and coaxially to the periphery of a passage transporting the product to be sprayed.

Claim 9

Apparatus according to claim 1, including means for picking up electric charges situated in the passage for the gas transporting the electric charges downstream of said electrode means and convergent-divergent portion, and electric conductor means electrically connecting said pickup means to a passage for transporting the product to be sprayed.

Claim 10

Apparatus according to claim 8, wherein the conductor means is in contact with the product to be sprayed.

Claim 11

Apparatus according to claim 9, wherein the conductor means and the pickup means comprises at least one wall of the spray nozzle.

Claim 12

Apparatus according to claim 8, wherein the conductor means terminates in an ionizing electrode protruding beyond the spray nozzle.

Claim 13

Apparatus according to claim 1, wherein the high-voltage generator is constructed as a detachable cartridge.

Claim 14

Apparatus according to claim 3, wherein the means for injecting the volatile liquid is a wick immersed in a tank and discharging into the passage.

Claim 15

Apparatus according to claim 1, in which said nozzle is rotatable and driven in rotation by said gaseous fluid.

Claim 16

Electrostatic spraying apparatus comprising a body carrying a spray nozzle, a passage in said body leading to the region of said nozzle, a convergent-divergent portion located upstream of said passage, an electrode arranged adjacent said convergent-divergent portion, means for applying a voltage to said electrode, means for feeding a gaseous fluid to said convergent-divergent portion so as to impart a supersonic speed to at least part of said fluid, as said fluid passes along said passage carrying an electric charge to the region of said spray nozzle.

Claim 17

Electrostatic spraying apparatus comprising a body carrying a spray nozzle, a passage in said body leading to the region of said nozzle, a convergent-divergent portion located upstream of said passage, an electrode arranged adjacent said convergent-divergent portion, means for applying a voltage to said electrode, means for feeding a gaseous fluid to said convergent-divergent portion so as to impart a supersonic speed to at least part of said fluid, as said fluid passes along said passage carrying an electric charge to the region of said spray nozzle.

Claim 18

In electrostatic spraying apparatus, a high-voltage generator comprising a passage, a convergent-divergent portion communicating with said passage, electrode means adjacent said convergent-divergent portion, means for applying a voltage to said electrode means, and means for feeding a gaseous fluid to pick up electric charges from said electrode means and so that said charged fluid flows down said passage at least partially at supersonic speed.

Claim 19

In electrostatic spraying apparatus, a high-voltage generator comprising a passage, a convergent-divergent portion communicating with said passage, electrode means adjacent said convergent-divergent portion, means for applying a voltage to said electrode means, and means for feeding a gaseous fluid to pick up electric charges from said electrode means and so that said charged fluid flows down said passage at least partially at supersonic speed.

Claim 20

Electrostatic spraying apparatus including a spray nozzle and a high-voltage generator, said generator comprising a barrel made of insulating material and defining a passage adapted to carry a pressurized gaseous fluid from a source of such fluid to said nozzle, and electrode means in said passage for transmitting electrical charges to said fluid, said passage having a convergent-divergent portion adjacent said electrode which imparts a supersonic speed to at least part of said gaseous fluid.

Claim 21

Electrostatic spraying apparatus including a spray nozzle and a high-voltage generator, said generator comprising a barrel made of insulating material and defining a passage adapted to carry a pressurized gaseous fluid from a source of such fluid to said nozzle, and electrode means in said passage for transmitting electrical charges to said fluid, said passage having a convergent-divergent portion adjacent said electrode which imparts a supersonic speed to at least part of said gaseous fluid.

Claim 22

Electrostatic spraying apparatus as claimed in claim 17 comprising a counterelecrode in said passage adjacent said electrode and adapted to be connected to ground.

Claim 23

Electrostatic spraying apparatus as claimed in claim 18 in which said counterelectrode defines said convergent-divergent portion.

Claim 24

Electrostatic spraying apparatus as claimed in claim 18 in which a barrel defines a second passage for conducting a material to be sprAyed from a source of such material to said nozzle, and said nozzle comprises means for causing said gaseous fluid to impinge on said material to be sprayed, and thereby transmit thereto electrical charges transmitted to said fluid by said electrode.

Claim 25

Electrostatic spraying apparatus as claimed in claim 18 in which said barrel defines a second passage for conducting material to be sprayed to said nozzle and said nozzle comprises electrically conductive means positioned adjacent the ends of said passages to contact both said gaseous fluid and said material to be sprayed, and thereby transmit to said material to be sprayed electrical charges acquired by said fluid from said electrode.

Claim 26

Electrostatic spraying apparatus as claimed in claim 18 comprising means for introducing a material to be sprayed into said passage upstream of said convergent-divergent portion.

Claim 27

Electrostatic spraying apparatus as claimed in claim 18 comprising means for introducing a material to be sprayed into said passage upstream of said electrode.

Claim 28

Electrostatic spraying apparatus as claimed in claim 18 in which said barrel defines a chamber connecting said passage to said nozzle and comprising an additional passage for material to be sprayed which terminates in said chamber.

Claim 29

Electrostatic spraying apparatus as claimed in claim 18 in which said electrode is upstream of said convergent-divergent portion and comprising means for introducing a material to be sprayed into said passageway upstream of said convergent-divergent portion but downstream of said electrode.

Claim 30

Electrostatic spraying apparatus as claimed in claim 21 in which said nozzle comprises a head of insulating material defining a separate opening aligned with each passage, and said electrically conductive means is a conductor extending into both openings.

Claim 31

Electrostatic spraying apparatus as claimed in claim 21 in which said nozzle comprises an electrically conductive part defining an opening aligned with said second passage, and positioned to be contacted by fluid emerging from the passage having said convergent-divergent portion.

Claim 32

Electrostatic spraying apparatus as claimed in claim 21 in which said nozzle is electrically conductive, and the passage containing said electrode reaches said nozzle through a conductive collector ring electrically connected to the walls of said nozzle, said nozzle being provided with a deflector positioned to deflect said material to be sprayed against the wall of said nozzle, whereby electrical charges imparted to said gaseous fluid by said electrode are conducted from said gaseous fluid by said collector to said nozzle and imparted by said nozzle to said material to be sprayed.

Claim 33

Electrostatic spraying apparatus as claimed in claim 18 in which said nozzle comprises an electrically conductive part at the end of said second passage, the passage having said convergent-divergent portion being divided into two branches downstream of said convergent-divergent portion, with one of said branches leading to said nozzle so as to conduct to said nozzle particles of gaseous fluid charged by said electrode, and the other bypassing said nozzle and leading to the ambient atmosphere, and said apparatus further comprising an electrical conductor athwart said other branch and leading to the electrically conductive part of said nozzle.

Claim 34

Electrostatic spraying apparatus as claimed in claim 18 in which said nozzle comprises a stationary electrically conductive part at the outlet of said second passage, and a rotatable charge collector made of electrically conductive material, said charge collector being positioned in electrical contact with said stationary electrically conductive part and comprising blades athwart the nozzle end of the passage having said convergent-divergent portion, whereby said gaseous fluid acquires an electrical charge from said electrode, is accelerated by said convergent-divergent portion, rotates said charge collector by impinging on said blades, and transmits to said charge collector, and through said charge collector to said stationary nozzle portion the electrical charge acquired from said electrode.

Claim 35

Electrostatic apparatus as claimed in claim 18 comprising valve means for controlling the flow of fluid in said passage.

Claim 36

Electrostatic apparatus as claimed in claim 21 comprising valve means for controlling the flow through each passage, and single actuating means for simultaneously actuating both valves.

Claim 37

In combination, electrostatic spraying apparatus as claimed in claim 18, a source of gaseous fluid under a pressure of several atmospheres connected to said passage, and a source of electric power connected to supply to said electrode an excitation voltage of several kilovolts.

Claim 38

Electrostatic spraying apparatus for use with a source of gaseous fluid under a pressure of several atmospheres and a source of direct voltage adapted to supply a voltage of several kilovolts, said spraying apparatus including a spray nozzle and a high-voltage generator, and said generator comprising a barrel made of insulating material, said barrel defining a passage for connecting said gaseous fluid source to said nozzle, an electrode in said passageway adapted to transmit electric charges from said voltage source to the gaseous fluid in said passage and a counterelectrode in said passageway adapted to be connected to ground, said passage having a convergent-divergent portion therein adjacent said electrode which imparts a supersonic speed to at least part of said gaseous fluid, thereby increasing the voltage of the electrical charges transitted thereto, and means for introducing a fluent material to be sprayed into said passage so that at least some of said electrical charges are transferred from said gaseous fluid to said material.

Claim 39

Electrostatic spraying apparatus for use with a source of gaseous fluid under a pressure of several atmospheres and a source of direct voltage adapted to supply a voltage of several kilovolts, said spraying apparatus including a spray nozzle and a high-voltage generator, and said generator comprising a barrel made of insulating material, said barrel defining a passage for connecting said gaseous fluid source to said nozzle, an electrode in said passageway adapted to transmit electric charges from said voltage source to the gaseous fluid in said passage and a counterelectrode in said passageway adapted to be connected to ground, said passage having a convergent-divergent portion therein adjacent said electrode which imparts a supersonic speed to at least part of said gaseous fluid, thereby increasing the voltage of the electrical charges transitted thereto, and means for introducing a fluent material to be sprayed into said passage so that at least some of said electrical charges are transferred from said gaseous fluid to said material.

Claim 40

Electrostatic spraying apparatus for use with a source of gaseous fluid under a pressure of several atmospheres and a source of direct voltage adapted to supply a voltage of several kilovolts, said spraying apparatus including a spray nozzle and a high-voltage generator, and said generator comprising a barrel made of insulating material, said barrel defining a passage for connecting said gaseous fluid source to said nozzle, an electrode in said passageway adapted to transmit electric charges from said voltage source to the gaseous fluid in said passage and a counterelectrode in said passageway adapted to be connected to ground, said passage having a convergent-divergent portion therein adjacent said electrode which imparts a supersonic speed to at least part of said gaseous fluid, thereby increasing the voltage of the electrical charges transmitted thereto, said barrel defining an additional passage adapted to lead a fluent material to be sprayed to said nozzle, and electrically conductive means positioned to conduct electric charges from said gaseous fluid to said fluent material to be sprayed.

Claim 41

Electrostatic spraying apparatus for use with a source of gaseous fluid under a pressure of several atmospheres and a source of direct voltage adapted to supply a voltage of several kilovolts, said spraying apparatus including a spray nozzle and a high-voltage generator, and said generator comprising a barrel made of insulating material, said barrel defining a passage for connecting said gaseous fluid source to said nozzle, an electrode in said passageway adapted to transmit electric charges from said voltage source to the gaseous fluid in said passage and a counterelectrode in said passageway adapted to be connected to ground, said passage having a convergent-divergent portion therein adjacent said electrode which imparts a supersonic speed to at least part of said gaseous fluid, thereby increasing the voltage of the electrical charges transmitted thereto, said barrel defining an additional passage adapted to lead a fluent material to be sprayed to said nozzle, and electrically conductive means positioned to conduct electric charges from said gaseous fluid to said fluent material to be sprayed.