LOW PRESSURE, FULL COVERAGE FLUIDIC SPRAY DEVICE

Abstract: A two-stage liquid spray device having an outlet region with an island (41) and an exit aperture (47) and a fluidic oscillator (33) driving said outlet region. The improvement for the spray device is operable at a low pressure to achieve full-area coverage with substantially uniform droplets and wherein all of the spray droplets land on the desired work surface and do not bounce. The fluidic oscillator includes an oscillation chamber (33), a power nozzle (31) for introducing a jet of liquid from a source into the oscillation chamber. The oscillation chamber is configured to produce a pair of alternating control vortices which substantially preclude wall attachment of said jet traversing said oscillation chamber, thus avoiding a heavy endedness in the oscillatory jet. An outlet from the oscillation chamber to the outlet region, whereby the jet rhythmically sweeps in end pulses to each side of the island and forms a sheet at the exit aperture. The sheet is rhythmically waved or swept in the ambient air to form the uniform droplets. A transverse slot defines the lateral boundary of the sweeping sheet.

Description: LOW PRESSURE, FULL COVERAGE FLUIDIC SPRAY DEVICE RELATED APPLICATION This application is a continuation-in-part application of copending application Serial No. 08/713,276 filed September 12, 1996 entitled LOW PRESSURE, FULL COVERAGE FLUIDIC SPRAY DEVICE. BACKGROUND OF THE INVENTION Fig. 1 hereof, from Stouffer Patent No. 4,151,955 (incorporated herein by reference), discloses a two-stage fluidic spray device in which a wall attachment, heavy- ended type of fluidic oscillator 10 drives a generally circular outlet region or chamber 11. Outlet region 11 has a substantially concentric island 12 which converts the fluidically swept jet issuing from fluidic oscillator to sweeping sheet. Fig. 2, from Stouffer Patent No. 4,508,267 (incorporated herein by reference) discloses a liquid oscillator for producing a unidirectional swept jet for producing a fan spray 16 with resulting liquid droplets of uniform size. Alternating control vortices are formed in the oscillation chamber 17 and preclude the wall attachment effects which make the fluidic oscillator portion or spray shown in Fig. 1 heavy-ended. We have discovered that a two-stage liquid spray device having an outlet region with an island of the type illustrated in Stouffer Patent No. 4,151,955 and a fluidic oscillator of the type shown in Stouffer Patent No. 4,508,267 can be operated at low pressure (as from a pumped source or a plastic squeeze container) to achieve full-area coverage with substantially uniform droplets and wherein all of the spray droplets land on the desired work surface and do not bounce. In other words, the liquid droplets stay on the work surface in the desired pattern. The exit aperture from the outlet stage to ambient is provided with a transverse groove to define the extent of the oscillating liquid sheet forming the spray. The object of the present invention is to provide a liquid spray device for full area coverage which operates at low pressure and velocity and which produces substantially uniform droplets in the full area coverage spray. According to a preferred embodiment of the invention, a two-stage fluidic spray device in which a fluidic oscillator has an oscillation chamber configured so that alternate control vortices cause a power jet to oscillate back and forth in the oscillation chamber without significant wall attachment effects. The output of the fluidic oscillator drives an island type output region. The exit aperture or opening from the outlet region to ambient is provided with an external transverse groove or slot which defines the lateral boundaries of the spray pattern of liquid and substantially eliminates any drip. BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, advantages and features of the invention will become more apparent when considered in conjunction with the following specifications and accompanying drawings, wherein: Fig. 1 (prior art) is a silhouette of a two-stage spray device disclosed in Fig. 20 of Stouffer Patent No. 4,151,955; Fig. 2 (prior art) is a silhouette of a fluidic oscillator disclosed in Stouffer Patent No. 4,508,267; Fig. 3 is a silhouette of a two-stage fluidic spray device incorporating the invention; Fig. 4 is a front elevational view of a two-stage spray device incorporating the invention; and Fig. 5 is an isometric perspective view of a two-stage spray device incorporating the invention. DETAILED DESCRIPTION OF THE INVENTION Referring now to Fig. 3, a two-stage liquid spray device 30 incorporating the invention has a power nozzle 31 coupled via passage 32 to a source of liquid to be sprayed or dispersed in a predetermined pattern onto a desired surface. The source S may be a pumped source or a plastic squeeze bottle or other source of liquid. The liquid can be a wash/wax, water, etc. liquid. Power nozzle 31 has converging side walls SW and issues a jet of liquid into oscillation chamber 33. As described is Stouffer Patent No. 4,508,267, alternating control vortices are formed in the oscillation chamber 33 with the alternating vortices controlling the flow of liquid in control passages 34 and 35 and control ports 36 and 37 causing the liquid jet to rhythmically oscillate back and forth in the oscillation chamber 33. The jet of liquid is swept or oscillated in outlet 38 which constitutes the inlet to outlet region 39 which is constituted by a generally circular (in this embodiment) outlet chamber 40 having outlet island 41. The rhythmic sweeping of the jet of liquid in outlet 38 causes the rhythmic pulsing of liquid in the passages 42 and 43 on the two sides of the island 41 to impinge at tip or point 44 thus producing an oscillating sheet 46 oriented perpendicular to the impingement direction of the liquid jets at the exit 47. The oscillating sheet of liquid 46 breaks up into uniform droplets 50 thus providing a uniform coverage over a predetermined area of the deposit surface. The end of the nozzle is diamond-shaped as shown in Figs. 4 and 5, and laterally extending groove or channel 60 is provided to define the boundary of the oscillating sheet where it leaves exit 47 to obtain the desired shape of the spray. The groove 60 is also designed to drain off the accumulating liquid at the edges. The slot or groove 60 geometry produces the required expansion of the oscillating sheet of liquid issuing to ambient through the outlet aperture 47. While I have shown and described preferred embodiments of the invention, it will be appreciated that other embodiments, modifications and adaptations of the invention will become readily apparent to those skilled in the art.

Claims: WHAT IS CLAIMED IS: 1. A two-stage liquid spray device having an outlet region with an island and an exit aperture and a fluidic oscillator, driving said outlet region, the improvement for operating said spray device at low pressure and achieve full-area coverage with substantially uniform liquid droplets and wherein all of the spray droplets land on the desired work surface and do not bounce, and wherein said fluidic oscillator includes an oscillation chamber, a power nozzle for introducing a jet of liquid from a liquid source into said oscillation chamber, said oscillation chamber being configured to produce a pair of alternating control vortices which substantially preclude wall attachment effects of said jet traversing said oscillation chamber, and an outlet from said oscillation chamber to said outlet region, whereby said jet rhythmically sweeps in said outlet and rhythmical pulses on each side of said island to said exit aperture, and a sheet of liquid is swept to form said uniform droplets. 2. The spray device defined in Claim 1 including a slot extending transverse to said exit aperture for defining the boundary of said sweeping sheet.

Inventors: RAGHU SURYA, STOUFFER RONALD D, RAGHU, SURYA, STOUFFER, RONALD, D.
Applicants: BOWLES FLUIDICS CORP, BOWLES FLUIDICS CORPORATION
Application year: 1997
Main classification: B05B1
IPC codes: B05B1, F15C1