REVERSING CHAMBER OSCILLATOR

Abstract: A reversing chamber (IC) oscillator has an oscillation chamber (IC) with a reversing wall (RW), a centrally located power nozzle (PN) for issuing a jet of liquid toward the reversing wall (RW), and a pair of liquid passages (CH1, CH2) from the reversing chamber (IC) on each side of the power nozzle (PN), respectively, for alternately issuing periodic pulses of liquid. The outlet passages (CH1, CH2) are smoothly extended to intersect at a common outlet (CO) to ambient and are dimensioned and angulated relative to each other to control the fan angle of a liquid jet which is periodically swept in the common outlet (CO) and sprayed to ambient. The pair of fluid passages (CH1, CH2) have an upstream end at the reversing chamber (IC) and a downstream end at the common outlet (CO) and each passage (CH1, CH2) has an outer wall which, with the reversing wall (RW), define an oval.

Description: REVERSING CHAMBER OSCILLATOR REFERENCE TO RELATED APPLICATIONS This invention is the subject of provisional application Serial No. 60/105,948 filed October 28, 1998 and entitled REVERSING CHAMBER OSCILLATOR. BACKGROUND AND BRIEF DESCRIPTION OF THE INVENTION The present invention relates to reversing chamber fluidic oscillators of the type in which a reversing chamber oscillator issues discrete pulses of fluid in alternation from two or more outlet openings as disclosed in Patent No. 4,184,636 for example, which is incorporated herein by reference. SUMMARY OF THE INVENTION According to the present invention, the reversing chamber fluidic oscillator incorporates a pair of outlet passages from the reversing chamber which outlet passages lead smoothly and in a gradually curved manner, without sharp significant changes in direction, to intersect at a common outlet. Each of the outlet passages has an upstream end beginning at the reversing chamber and a downstream end at the common outlet. Each outlet passage first gradually narrows to a minimum cross-sectional area and then gradually expands to a maximum cross-sectional area at the common outlet. The common outlet has a pair of sidewalls which diverge in a downstream direction toward ambient. The reversing chamber has a power nozzle inlet and a far wall surface opposite the power nozzle which serves as a reversing wall. The reversing chamber, with its outside wall or reversing chamber wall surface, and the outer surfaces of the pair of outlet passages define an oval shape. Thus, the object of the invention is to provide a liquid spray device having a reversing chamber oscillator having an oscillation chamber with a reversing wall and a power nozzle for issuing a liquid jet towards the reversing wall. A pair of liquid passages or channels lead smoothly from the reversing chamber on each side of the power nozzle and carry discrete liquid pulses in alternation through the two channels. The outlet passages or channels are smoothly extended to intersect at a common outlet to ambient and are dimensioned and angulated relative to each other at the common outlet to control the fan angle of the merged liquid jets which is periodically swept in the common outlet opening to ambient. Moreover, the liquid passages each have an upstream end at the reversing chamber and a downstream end at the common outlet. Each passageway has an outer wall, which, with the reversing wall, define an oval. The jet of merged liquid is swept in the common outlet, and the passages and angulations are such that the mean droplet size in the operating fluid pressure range of from 5 - 30 psi remains above about 1500 microns. DESCRIPTION OF THE DRAWINGS The above and other objects, advantages and features of the invention will become more apparent when considered with the following specification and accompanying drawings wherein: Figure 1 is a top plan view of a reversing chamber oscillator incorporating the invention, with a portion of the cover removed to expose the internal silhouette or fluidic oscillator circuit, Figure 2A is a diagrammatic sketch of an automobile windshield washer system in which the invention has been incorporated, Figure 2B is a diagrammatic illustration of a "wet arm" windshield washer system wherein the nozzles are mounted on the arms of the wiper blades, and Figure 2C is a diagrammatic sketch of a headlamp washer system incorporating the invention. DETAILED DESCRIPTION OF THE INVENTION Referring to Figure 1, the fluidic oscillator incorporated in the molded plastic body member 10 has a reversing chamber power nozzle N for projecting a liquid jet from a source such as the washer fluid source as shown in Figure 2A, 2B and 2C, towards a reversing wall RW. A cover or housing member H is shown partially removed. A pair of counter-rotating vortices are produced in the interaction chamber IC and the jet of the liquid is transported around these vortices towards the exits. The instability of the jet causes the vortices to change in size and the asymmetric vortices in turn cause the jet to deflect by a large amount thus setting up the oscillation process. A pair of liquid passages CHI and CH2 lead from the reversing or intersection chamber IC on each side of the power nozzle PN respectively. These outlet passages are smooth, and without any sharp directional changes, and extend to intersect at a common outlet CO which has a pair of diverging sidewalls SW1 and SW2. It will be noted that the pair of outlet passages CHI and CH2 lead smoothly and are gradually curved without sharp and significant changes in direction to intersect at a common outlet. Each of the outlet passages CHI and CH2 have an upstream beginning at the reversing chamber and a downstream end at the common outlet CO. Each passage first smoothly and gradually narrows to a minimum cross-sectional area and then gradually and smoothly expands to a maximum cross-sectional area at the common outlet. It will be noted that the reversing chamber has a power nozzle inlet and the far wall reversing surface RW opposite the power nozzle inlet with the outside wall surfaces of the pair of outlet passages CHI and CH2 defining an oval shape. The invention has the following features: 1. The area ratio between the throat and the power nozzle is significantly high of the order of 2 to 4 compared to that of the conventional fluidic nozzle where it is a maximum of around 2.0. This large area ratio permits formation of larger drop sizes in the reversing chamber oscillator. The large throat area also reduces the clogging chances by a factor of at least two. This is because there is only one small flow restriction (power nozzle) in the device compared to three in the conventional device. Further, the power nozzle has the largest velocity to flush out any clogging material while there is no restricting or obstructing passages in the vicinity of the power nozzle exit. 2. There is a reduction of momentum due to the change of direction of the primary liquid jet in the reversing chamber portion of the device. This results in a lower velocity flow of the liquid which reduces ricochet of the drops from the impact surface. This is advantageous in cleaning spray nozzles. 3. The volume mean diameter of the droplets are significantly larger by about 500 microns compared to the conventional feedback fluidic nozzles of comparable flow rates. 4. There is less deviation of the droplet size from the mean droplet size as measured by the quantity defined as "uniformity". Uniformity of droplet size distribution (as opposed to uniformity of spray distribution) is a measure of the dispersion of the droplet diameter around the mean diameter. The smaller the value of uniformity, the smaller the range of diameters. 5. There are also less number of fine size droplets (<400 microns) in the reverse oscillator of this invention. 6. The frequency of oscillation for a given flow rate is significantly smaller (by a factor of three) for the reversing chamber oscillator of this invention. 7. The reversing chamber oscillator provides a better platform (simplicity) for manufacturing electrically heated spray nozzles. 8. There is no spray attachment to the sides of the nozzle even for very large spray fan angles of up to 120°, and this minimizes dripping from the sides of the nozzle exit. While the invention has numerous applications, it is particularly useful in liquid spray applications such as vehicle windshields, rear windows and headlamps. In Figure 2A, the oscillator is incorporated in a washer system nozzle 11 (which may be electrically heated) coupled by a tube 19 to a pump 13 and reservoir 16 of wash liquid 14. In Figure 2B, the nozzles with reversing chamber oscillators of this invention are mounted on the wiper arms 12L and 12R. In Figure 2C, the nozzles HN are mounted on a mechanical traversing arms TA of a headlamp washer system. While a preferred embodiment of the invention has been illustrated and described, it will be appreciated that other adaptations, embodiments and modifications to the invention will be readily apparent to those skilled in the art.

Claims: WHAT IS CLAIMED IS: 1. In a reversing chamber oscillator having an oscillation chamber with a reversing wall, a centrally located power nozzle for issuing a jet of liquid toward said reversing wall, and a pair of liquid passages from said reversing chamber on each side of said power nozzle, respectively, for alternately issuing periodic pulses of liquid, the improvement wherein said outlet passages are smoothly extended to intersect at a common outlet to ambient and are dimensioned and angulated relative to each other to control the fan angle of a liquid jet which is periodically swept in said common outlet to ambient. 2. In a washer spray nozzle, the reversing chamber oscillator defined in Claim 1 wherein said liquid is a wash liquid which breaks up into droplets as said fluid jet is swept in said common outlet to ambient and said passages and angulations are such that the mean droplet size, in an operating fluid pressure range of 5 - 30 psi, remains above 1500 microns. 3. The reversing chamber oscillator defined in Claim 1 wherein each said pair of fluid passages have an upstream end at said reversing chamber and a downstream end at said common outlet, each said passage having an outer wall which, with said reversing wall, define an oval.

Inventors: RAGHU SURYA, RAGHU, SURYA
Applicants: BOWLES FLUIDICS CORP, BOWLES FLUIDICS CORPORATION
Application year: 1999
Main classification: B05B1
IPC codes: B05B1, B60S1, F15C1