Heat-resistant broad-bandwidth liquid droplet generators
First Claim
1. A liquid droplet generator, comprising:
- a delivery tube having a wall and an exit orifice;
an electromechanical driver element disposed to transmit pressure pulses to said wall;
a power supply coupled to said electromechanical driver; and
a high-temperature heat source thermally coupled to said delivery tube, said high-temperature heat source adapted to heat said delivery tube to temperatures in excess of the Curie temperature of a piezoelectric material.
1 Assignment
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Accused Products
Abstract
Apparatus and methods for making uniformly-sized and predictably-spaced droplets from high-temperature liquids. Liquid droplet generators having electromechanical driving elements are coupled to a power supply to apply pulsed excitation forces through a wall of a delivery tube to a high-temperature liquid, e.g., a liquid metal, epoxy, or polymer. The excitation forces generated by the driver induce capillary vibrations in the liquid within the delivery tube. Liquid jet streams having capillary vibrations when exiting an orifice break up into groups of substantially uniformly-sized liquid droplets shortly after leaving the orifice. Droplets may be produced in a uniformly-spaced series, or individually on demand in response to a single burst of force from the driving element. A heat source is also thermally coupled to the delivery tube to maintain the liquid in a high-temperature state. Embodiments using heat-sensitive elements thermally insulate those elements from the wall of the heated delivery tube and may also actively cool the elements by one or more heat exchangers. A magnetohydrodynamic embodiment couples a magnetic field, having spaced points of maximum intensity, to a fluid stream exiting an orifice, causing the stream to break into droplets in response to the periodic magnetic field.
182 Citations
42 Claims
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1. A liquid droplet generator, comprising:
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a delivery tube having a wall and an exit orifice; an electromechanical driver element disposed to transmit pressure pulses to said wall; a power supply coupled to said electromechanical driver; and a high-temperature heat source thermally coupled to said delivery tube, said high-temperature heat source adapted to heat said delivery tube to temperatures in excess of the Curie temperature of a piezoelectric material. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A liquid droplet generator, comprising:
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a delivery tube having a wall and an exit orifice; an electromechanical driver element disposed to transmit pressure pulses to said wall; and a power supply coupled to said electromechanical driver element; wherein said electromechanical driver element comprises; current windings circumferentially surrounding said delivery tube and acoustically coupled thereto, said current windings comprising a first current winding adjacent to a second current winding, said current windings also coupled to said power supply; electrical insulation disposed between said first and second current windings; wherein said first and second current windings are disposed so that a current travelling through said first winding will be of opposite polarity to a current travelling through said second winding; and a force retaining ring substantially surrounding said current windings. - View Dependent Claims (8, 9, 10)
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11. A liquid droplet generator, comprising:
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a delivery tube having a wall and an exit orifice; an electromechanical driver element disposed to transmit pressure pulses to said wall; and a power supply coupled to said electromechanical driver element; wherein said electromechanical driver element comprises; an electromagnetic field generator substantially surrounding the circumference of said delivery tube; and an armature circumferentially coupled to said delivery tube and proximate to said electromagnetic field generator, said armature comprising soft magnetic material. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A liquid droplet generator, comprising:
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a delivery tube having a wall and an exit orifice; an electromechanical driver element disposed to transmit pressure pulses to said wall; and a power supply coupled to said electromechanical driver element; wherein said electromechanical driver element comprises; an insulator coupled to said delivery tube and circumferentially surrounding said delivery tube over a portion of the length of said delivery tube, said insulator comprising an acoustically conductive, thermally insulating material; a first conductor substantially surrounding said insulator and coupled thereto; a dimension-changing means coupled to said first conductor; a force retaining ring of electrically conductive material substantially surrounding said dimension-changing means and coupled thereto; said first conductor and said force retaining ring coupled to said power supply; and cooling means disposed to draw heat away from said first conductor and said force retaining ring. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26)
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27. A liquid droplet generator, comprising:
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a delivery tube having a wall and an exit orifice, said delivery tube adapted to transmit a liquid jet stream through said exit orifice; an electromechanical driver element disposed to receive said liquid jet stream, said driver element comprising; a magnetic field yoke having arms corresponding to points of maximum field intensity; and current windings disposed about a portion of said magnetic field yoke; and a power supply coupled to said current windings of said electromechanical driver element. - View Dependent Claims (28, 29, 30)
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31. A high-temperature liquid droplet generator, comprising:
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a chamber adapted to receive a high-temperature liquid having a temperature in excess of the Curie temperature of a piezoelectric material, said chamber including a discharge orifice at one end; a heater positioned proximate the chamber and operable to maintain the high-temperature liquid inside the chamber at about said high temperature; and a pulsing energy source coupled to the chamber, said pulsing energy source being operable in a tuned relation with the chamber and the high-temperature liquid therein to generate pressure pulses in the liquid so as to discharge the liquid from the chamber as droplets related in number to the pressure pulses producing the droplets. - View Dependent Claims (32, 33)
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34. A method for generating droplets from a high-temperature liquid, comprising:
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delivering a high-temperature liquid having a temperature in excess of the Curie temperature of a piezoelectric material to a liquid droplet generator in a jet, the liquid droplet generator comprising; a delivery tube having a wall and an exit orifice, said delivery tube adapted to receive said liquid jet; and an electromechanical driver element coupled to said wall; electrically exciting said electromechanical driver element to compress said wall; and expelling at least one liquid droplet from said exit orifice. - View Dependent Claims (35, 36)
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37. A method for generating liquid droplets, comprising:
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delivering liquid to a liquid droplet generator in a jet, the liquid droplet generator comprising; a delivery tube having a wall and an exit orifice, said delivery tube adapted to receive said liquid jet; and an electromechanical driver element coupled to said wall; electrically exciting said electromechanical driver element to compress said wall; and expelling at least one liquid droplet from said exit orifice; wherein said electromechanical driver element comprises a piezoelectric crystal acoustically coupled to said wall and thermally insulated from said wall. - View Dependent Claims (38)
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39. A method for generating liquid droplets, comprising:
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delivering liquid to a liquid droplet generator in a jet, the liquid droplet generator comprising; a delivery tube having a wall and an exit orifice, said delivery tube adapted to receive said liquid jet; and an electromechanical driver element coupled to said wall; electrically exciting said electromechanical driver element to compress said wall; and expelling at least one liquid droplet from said exit orifice; wherein said exciting and expelling steps comprise; supplying pulsed current to said driver; generating a pulsed magnetic field substantially and symmetrically surrounding said delivery tube in response to said pulsed current; alternately expanding and contracting a portion of said wall of said delivery tube radially in response to said pulsed magnetic field; vibrating said liquid jet in said delivery tube in response to said expansion and contraction; inducing a waveform on said liquid jet in said delivery tube in response to said vibrations; and amplifying said waveform to cause said liquid jet to break into droplets after exiting said orifice.
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40. A method for generating liquid droplets, comprising:
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delivering liquid to a liquid droplet generator in a jet, the liquid droplet generator comprising; a delivery tube having a wall and an exit orifice, said delivery tube adapted to receive said liquid jet; and an electromechanical driver element coupled to said wall; electrically exciting said electromechanical driver element to compress said wall; and expelling at least one liquid droplet from said exit orifice; wherein said electromechanical driver element comprises a magnetostrictive element acoustically coupled to said wall and thermally insulated from said wall. - View Dependent Claims (41)
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42. A method of generating liquid droplets, comprising:
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delivering liquid to a liquid droplet generator in a jet, the generator comprising; a delivery tube having a wall and an exit orifice; an electromagnetic driver element disposed to receive said liquid jet stream, said driver element comprising; a magnetic field yoke having a plurality of arms at spaced intervals; and current windings disposed about a portion of said magnetic field yoke; heating said delivery tube; supplying current to said current windings of said driver element; generating a magnetic field from said magnetic field yoke, said magnetic field having maximum points of maximum field intensity corresponding to said arms of said field yoke; transmitting a liquid jet stream through said exit orifice and through said magnetic field; and breaking the liquid jet stream into a series of droplets in response to said magnetic field, said droplets having a spacing corresponding to the spacing of said points of maximum field intensity.
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Specification