US 4,398,672 AGranted

Electrostatic spraying

AssigneeNational Research Development Corporation

InventorsArthur J. Arnold, Barry J. Pye

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Abstract

An electrostatic crop spraying apparatus is arranged so that spray is ejected from the nozzle directly towards the crop, either vertically downwards or at an angle intermediate between the horizontal and the vertical. With respect to the vertical, the spray liquid is fed to the upper surface of a rotatable disc from which it is centrifugally distributed on to the inner surface of a rotatable hollow cone coaxial with the disc. The truncated apex of the cone is uppermost and the liquid is atomized on ejection from the lower circumferential edge of the cone. Charging of the spray is produced at the surface of the disc or of the cone by means of an electrode which maintains an ionized air path to the surface over a distance of a few mm. The current flow for an electrode potential in the range 15 to 30kV is a few .mu.A. A pump may be used to supply liquid to the nozzle in a pulsed flow.

Claims15

Dependent claims

An apparatus for the electrostatic spraying of liquid, the apparatus comprising:

inlet means for admitting a supply of liquid;
a first rotatable member having a distribution surface, said surface being disposed to receive the liquid from the inlet means for centrifugal distribution;
a second rotatable member having an internal conical surface, said conical surface being disposed coaxially with said distribution surface to receive the liquid from said distribution surface for centrifugal atomisation from a circumferential edge of said conical surface, and said circumferential edge being disposed with respect to said first member in that axial direction which is remote from said distribution surface;
means to support the first and second members in a spaced relationship to form a gap across which the centrifugal distribution occurs.
a terminal for the supply of electrostatic energy to an electrode means:
a said electrode means for conveying charge to a liquid layer at at least one of said distribution surface and said conical surface such that the spray of atomised particles from said circumferential edge is electrically charged;
an electrostatic feed path through the apparatus from said terminal to said electrode and onward to said circumferential edge including an air gap to electrically separate said edge from said terminal.

4 more elements

Dependencies are inferred from the claim text.