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US 4,343,433 AGranted
Internal-atomizing spray head with secondary annulus suitable for use with induction charging electrode
AssigneePPG Industries, Inc.
InventorJames E. Sickles
Life of this patent
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Abstract
A spray head for use with conventional air-atomizing spray equipment is disclosed which has spray-forming means that includes a secondary atomization annulus which provides improved atomization of liquid materials and which is especially suitable for spray devices having electrostatic induction charging means. The secondry annulus minimizes deposition on the spray head of particles electrically charged with a polarity opposite that of components of the spray head and provides re-atomization of sprayable material which collects on the walls of the nozzle.
Claims12
A spray head of the internal-atomizing type adaptable for use on induction charging air-atomization spray apparatus suitable for applying a spray stream of particles of liquid material to a substrate, comprising:
- a fluid delivery nozzle body having upstream and downstream ends and having passageways for transferring under pressure separate streams of air and of liquid material between said upstream and downstream ends;
- means for operatively connecting the upstream ends of the passageways of said fluid delivery nozzle body to separate sources of air and of liquid material;
- a spray stream discharge nozzle body comprising a generally hollow frustum-like portion with a wide-mouthed upstream end in which said fluid delivery nozzle body is nested and a narrower downstream end;
- an air cap body having a downstream-oriented substantially planar exterior face and having a hollow interior portion between an upstream wide-mouthed open end and a narrower downstream end, in which said hollow portion of said spray stream discharge nozzle body is nested;
- an orifice in the narrower downstream end of the hollow portion of said air cap body;
- a spray stream discharge nozzle extension protruding downstream from the downstream end of said spray stream discharge nozzle body, said nozzle extension terminating in a spray stream discharge port;
- an atomization chamber within said spray stream discharge nozzle body having an upstream inlet for receiving a stream of liquid material and having a downstream outlet orifice in communication with the passageway of said spray stream discharge nozzle extension;
- a liquid stream delivery nozzle extension downstream from the downstream end of said fluid delivery nozzle body, said nozzle extension being of dielectric material and having an outlet orifice in communication with the upstream end of said atomization chamber for delivery of a stream of liquid material into said atomization chamber;
- a first annular orifice in said atomization chamber inlet for delivering a stream of atomizing air for mixing with a stream of liquid material, said orifice defined by a downstream portion of the liquid delivery nozzle extension and the atomization chamber inlet;
- induction charging means in said atomization chamber connectable to a direct current high voltage source for inducing electrostatic charge upon air-atomized particles formed from a stream of liquid material as said particles are formed;
- and
- a second annular orifice for delivering a stream of atomizing air for mixing with said spray stream of atomized liquid material discharged from the spray stream discharge port, said second annular orifice defined by a portion of the downstream end of the spray stream nozzle extension and said air cap body orifice.
9 more elements
A process for forming liquid material into a spray stream of gas-atomized particles, which process employs an atomization chamber including
- (i) upstream and downstream ends and sidewalls,
- (ii) liquid inlet means of dielectric material comprising an orifice in said upstream end of said atomization chamber,
- (iii) gas inlet means comprising a first annular orifice concentrically disposed about said orifice of said liquid inlet means, and
- (iv) spray outlet means comprising an orifice at said downstream end of said atomization chamber and having an axis,
- said process comprising the steps of:
- (1) delivering a stream of liquid material through said liquid inlet means into a region of said atomization chamber,
- (2) delivering a first stream of gas through said gas inlet means into said region of said atomization chamber,
- (3) atomizing said liquid material by the coaction of said first gas stream which has a relatively high velocity with said stream of liquid material which has a relatively low velocity, to form gas-atomized particles within said region of said atomization chamber;
- (4) inducing electrostatic charge upon said gas atomized particles as said particles are formed within said region of said atomization chamber,
- (5) confining said gas-atomized particles in a stream as said particles are thrust from said atomization chamber in a spray,
- (6) delivering a second stream of gas through a second annular orifice concentrically disposed about said orifice of said spray outlet means and into contact with said spray to provide further atomization of gas-atomized particles.
8 more elements
Dependencies are inferred from the claim text.