Fluid sprinkling – spraying – and diffusing – With means to vibrate or jiggle discharge – By electric transducer
Reexamination Certificate
2000-02-08
2001-11-13
Scherbel, David A. (Department: 3752)
Fluid sprinkling, spraying, and diffusing
With means to vibrate or jiggle discharge
By electric transducer
C137S013000, C137S828000, C251S129060, C239S011000
Reexamination Certificate
active
06315215
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method of forming a spray of liquid. The present invention also relates to an apparatus for forming a spray of liquid.
Ultrasonic spray equipment is known. Examples include molding equipment, humidifiers and medical nebulizers. In some conventional devices, a pressurized stream of liquid is directed against an ultrasonically vibrating surface to produce a highly atomized spray of liquid. In other conventional devices, a spray nozzle or airblast atomizer may be ultrasonically vibrated to enhance spray formation. Generally speaking, devices of this type are configured such that the operating passage or orifice through which liquid flows is sonically live or vibrated. Utilizing spray equipment with a sonically live operating passage or orifice can add complexity to the design and operation of the equipment. For example, the dimensions of the operating passage, nozzle and supports need to be taken into consideration when determining energization frequencies and power requirements. As another example, some applications may require isolation of the sonically live operating passage from other non-vibrating elements of the equipment. Contact between the sonically live operating passage and a non-vibrating element may interfere with or interrupt operation.
SUMMARY OF THE INVENTION
The present invention provides an apparatus and a method for producing a liquid spray by applying ultrasonic energy to a portion of a pressurized liquid as it is received in a chamber and then passed through an orifice.
The apparatus includes a die housing which defines a chamber adapted to receive a pressurized liquid and a means for applying ultrasonic energy to a portion of the pressurized liquid. The die housing includes a chamber adapted to receive the pressurized liquid, an inlet adapted to supply the chamber with the pressurized liquid, and an exit orifice (or a plurality of exit orifices) defined by the walls of a die tip, the exit orifice being adapted to receive the pressurized liquid from the chamber and pass the liquid out of the die housing. Generally speaking, the means for applying ultrasonic energy is located within the chamber. For example, the means for applying ultrasonic energy may be an immersed ultrasonic horn. According to the invention, the means for applying ultrasonic energy is located within the chamber in a manner such that no ultrasonic energy is applied to the die tip (i.e., the walls of the die tip defining the exit orifice). That is, the means for applying ultrasonic energy is located within the chamber in a manner such that substantially no ultrasonic energy is applied to the die tip.
In one embodiment of the present invention, the die housing may have a first end and a second end. One end of the die housing forms a die tip having walls that define an exit orifice which is adapted to receive a pressurized liquid from the chamber and pass the pressurized liquid along a first axis. The means for applying ultrasonic energy to a portion of the pressurized liquid is an ultrasonic horn having a first end and a second end. The horn is adapted, upon excitation by ultrasonic energy, to have a node and a longitudinal mechanical excitation axis. The horn is located in the second end of the die housing in a manner such that the first end of the horn is located outside of the die housing and the second end is located inside the die housing, within the chamber, and is in close proximity to the exit orifice.
The longitudinal excitation axis of the ultrasonic horn desirably will be substantially parallel with the first axis. Furthermore, the second end of the horn desirably will have a cross-sectional area approximately the same as or greater than a minimum area which encompasses all exit orifices in the die housing. Upon excitation by ultrasonic energy, the ultrasonic horn is adapted to apply ultrasonic energy to the pressurized liquid within the chamber (defined by the die housing) but not to the die tip which has walls that define the exit orifice.
The present invention contemplates the use of an ultrasonic horn having a vibrator means coupled to the first end of the horn. The vibrator means may be a piezoelectric transducer or a magnetostrictive transducer. The transducer may be coupled directly to the horn or by means of an elongated waveguide. The elongated waveguide may have any desired input:output mechanical excitation ratio, although ratios of 1:1 and 1:1.5 are typical for many applications. The ultrasonic energy typically will have a frequency of from about 15 kHz to about 500 kHz, although other frequencies are contemplated.
According to the present invention, the ultrasonic horn may be composed of a magnetostrictive material. The horn may be surrounded by a coil (which may be immersed in the liquid) capable of inducing a signal into the magnetostrictive material causing it to vibrate at ultrasonic frequencies. In such cases, the ultrasonic horn can simultaneously be the transducer and the means for applying ultrasonic energy to the liquid.
In an aspect of the present invention, the exit orifice may have a diameter of less than about 0.1 inch (2.54 mm). For example, the exit orifice may have a diameter of from about 0.0001 to about 0.1 inch (0.00254 to 2.54 mm) As a further example, the exit orifice may have a diameter of from about 0.001 to about 0.01 inch (0.0254 to 0.254 mm).
According to the invention, the exit orifice may be a single exit orifice or a plurality of exit orifices. The exit orifice may be an exit capillary. The exit capillary may have a length to diameter ratio (L/D ratio) of ranging from about 4:1 to about 10:1. Of course, the exit capillary may have a L/D ratio of less than 4:1 or greater than 10:1.
In an embodiment of the invention, the exit orifice is self-cleaning even as it is adapted to produce a spray of liquid. According to the invention, the apparatus may be adapted to produce an atomized spray of liquid. Alternatively and/or additionally, the apparatus may be adapted to produce a uniform, cone-shaped spray of liquid.
The present invention encompasses a method of producing a liquid spray. The method involves supplying a pressurized liquid to the apparatus described above, exciting the means for applying ultrasonic energy with ultrasonic energy while the exit orifice receives pressurized liquid from the chamber (without applying ultrasonic energy to the die tip), and passing the pressurized liquid out of the exit orifice in the die tip to produce a liquid spray. That is, the exit orifice is adapted to produce a spray of liquid when the means for applying ultrasonic energy is excited with ultrasonic energy while the exit orifice receives pressurized liquid from the chamber and passes the liquid out of the die housing.
The present invention contemplates that the method steps of exciting the means for applying ultrasonic energy with ultrasonic energy (i.e., exciting the ultrasonic horn) while the exit orifice receives pressurized liquid from the chamber and passing the liquid out of the exit orifice in the die tip may further include the step of self-cleaning the exit orifice. The present invention contemplates that the step of passing the liquid out of the exit orifice in the die tip to produce a spray of liquid may include steps intended to produce sprays of liquid including, but not limited to, an atomized spray of liquid and a uniform, cone-shaped spray of liquid.
The apparatus and method of the present invention provide an advantage in that relatively viscous liquids (i.e., relatively viscous when compared to water, gasoline or diesel fuel at normal room temperature and pressures) can be readily sprayed or atomized from a coherent stream without conventional atomizing spray nozzles, air jets, rotating and/or vibrating impingement plates or the like. Utilizing the apparatus and method of the present invention, pressurized streams of liquid that are normally coherent in the absence of conventional atomizing or spray devices can be sprayed or atomized without directly changing or vibrating t
Cohen Bernard
Gipson Lamar Heath
Jameson Lee Kirby
Evans Robin O.
Garrison Scott B.
Kimberly--Clark Worldwide, Inc.
Scherbel David A.
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