Electrical generator

An electrical generator includes a passageway having an input port and at least one output port and at least one resonator for converting acoustic vibrations established in the passageway into mechanical vibrations of the resonator. The resonator is oriented adjacent at least one output port. A mechanical-to-electrical transducer is coupled to the resonator for generating electricity in response to the mechanical vibrations.

FIELD OF THE INVENTION

This invention relates to generators for generating electrical potentials.

BACKGROUND OF THE INVENTION

Various types of generators which employ piezoelectric transducers to generate electrical potentials are known. There are, for example, the devices illustrated and described in U.S. Pat. Nos. 4,248,386 and 3,666,976 and references cited in these. Various types of generators which employ fluid flow to generate electrical potentials are also known. There are, for example, the devices illustrated and described in U.S. Pat. Nos. 4,574,092, 4,498,631, 4,433,003, 4,020,393, 3,991,710, 3,791,579, 3,673,463, and 3,651,354 (generally electrogasdynamic potential supplies); and U.S. Pat. Nos. 4,290,091 and 4,219,865 (generally gas turbine driven generator/inverter/transformer/multiplier supplies and alternator/transformer/multiplier supplies), and U.S. Ser. No. 11/500,156, filed Aug. 7, 2006, titled Electric Power Generator, and assigned to the same Assignee as this application. There is also Richard G. Goldman,Ultrasonic Technology, Reinhold Publishing Corporation, New York, 1962, and particularly pages 94-102. The disclosures of these references are hereby incorporated herein by reference. This listing is not intended to be a representation that a complete search of all relevant art has been made, or that no more pertinent art than that listed exists, or that the listed art is material to patentability. Nor should any such representation be inferred.

DISCLOSURE OF THE INVENTION

According to an aspect of the invention, an electrical generator comprises a body providing a passageway having an input port and at least one output port, at least one resonator for converting acoustic vibrations established in the passageway into mechanical vibrations of the resonator, the at least one resonator oriented adjacent at least one output port, and a mechanical-to-electrical transducer coupled to the at least one resonator for generating electricity in response to the mechanical vibrations.

According to another aspect of the invention, an electrical generator comprises a body providing a passageway having an input port and at least one output port, at least one resonator for converting acoustic vibrations established in the passageway into mechanical vibrations of the resonator, the at least one resonator oriented outside at least one output port, and a mechanical-to-electrical transducer coupled to the at least one resonator for generating electricity in response to the mechanical vibrations.

According to another aspect of the invention, an electrical generator comprises a body providing a passageway having an input port and at least one output port, at least one resonator for converting acoustic vibrations established in the passageway into mechanical vibrations of the resonator, the at least one resonator oriented adjacent at least one output port and outside the passageway, and a mechanical-to-electrical transducer coupled to the at least one resonator for generating electricity in response to the mechanical vibrations.

Illustratively, the mechanical-to-electrical transducer does not lie along an axis of the passageway.

Illustratively, the passageway comprises a knife edge resonator

Alternatively illustratively, the passageway comprises a Hartmann generator.

Alternatively illustratively, the passageway comprises a Helmholtz resonator.

Alternatively illustratively, the passageway comprises a mechanical reed resonator.

Illustratively, the electrical generator includes multiple output ports and a resonator oriented adjacent each output port for converting acoustic vibrations established in the passageway into mechanical vibrations of the resonator.

Illustratively, there are multiple output ports oriented at different distances from the input port.

Illustratively, the resonators comprise flexible metal resonators.

Illustratively, the passageway includes a closed end.

Illustratively, the closed end includes a diffuser.

Illustratively, the closed end is closed by an adjustable plug.

Illustratively, the adjustable plug includes a diffuser.

Further illustratively, the electrical generator includes a diffuser and a spring between the diffuser and the adjustable plug.

Illustratively, the spring is characterized by a non-linear spring constant.

Illustratively, the spring constant takes into account the approximate variation of the speed of sound with temperature.

Further illustratively, the electrical generator includes a power conditioning device.

Illustratively, the power conditioning device comprises an inverter.

Additionally or alternatively illustratively, the power conditioning device comprises a transformer.

Additionally or alternatively illustratively, the power conditioning device comprises a rectifier.

Additionally or alternatively illustratively, the power conditioning device comprises a multiplier.

Illustratively, a utilization device is combined with the electrical generator.

Illustratively, the utilization device comprises an electrostatically aided coating material atomizing and dispensing device.

Illustratively, the at least one output port comprises at least one tuned waveguide.

Illustratively, the resonator comprises a thicker cross section near a center of the resonator.

Illustratively, the thicker section is provided by one of gluing an additional member adjacent the center, welding an additional member adjacent the center, chemical additive machining, chemical subtractive machining, mechanical additive machining and mechanical subtractive machining.

Illustratively, the thicker section comprises one of a stepped central region and a central region of gradually increasing thickness.

DETAILED DESCRIPTIONS OF ILLUSTRATIVE EMBODIMENTS

U.S. Pat. No. 3,666,976 describes a device that includes an air nozzle impinging on an annular knife edge/quarter wave resonant pipe. The pipe is terminated and closed opposite the nozzle end by a piezoelectric device that converts pressure fluctuations to electrical energy. Terminating a closed air column with a piezoelectric transducer in the manner described in U.S. Pat. No. 3,666,976 results in certain compromises in overall efficiency. A more effective closed resonator configuration results if the transducer/end presents a substantial acoustic impedance mismatch with the air in the column. Such a configuration provides the reflection needed for resonance. However, an impedance match is more desirable to efficiently convert pressure fluctuations to electrical energy. Thus efficient electrical power transfer must be compromised to maintain air column resonance.

Further, devices which produce resonating columns of air radiate a substantial amount of acoustic energy as acoustic waves. This energy is not used effectively in the prior art.

Referring toFIG. 1, according to an embodiment of the invention, arrays of one or more transducers20, such as piezoelectric ceramic unimorph or bimorph transducers, are arranged adjacent openings22to atmosphere around a passageway24, and not coaxially with the passageway24. The passageway24has a closed end26not terminated in a transducer20. With this configuration, the transducers20convert energy that is lost in prior art devices as acoustic radiation. The transducers20are attached, for example, by gluing with suitable adhesive(s), such as cyanoacrylate adhesive or the like, to knife edges28formed at the ends of respective tubes30. The transducers20are joined to knife edges28at vibrational nodes of the transducers20so as not to unduly affect the vibrations of the transducers20. Each transducer20is attached, for example, by gluing with suitable adhesive(s), such as cyanoacrylate adhesive or the like, to the adjacent flat face of a disk36of, for example, brass or other suitable material. The apex40of a somewhat dome-shaped flexible resonator34constructed from, for example, aluminum, is attached, for example, by gluing with suitable adhesive(s), such as cyanoacrylate adhesive or the like, to the opposite face of disk36opposite the center38of its respective transducer20.

Driving fluid, for example, a subsonic, transonic or supersonic jet of air, is directed into the open end44of passageway24, establishing the resonant column of air to drive the vibrations of transducers20which produce electrical current which is then supplied to a utilization device48,FIG. 2a. The electrical current may be coupled to input terminals of suitable power conditioning equipment50such as, for example, (an) inverter(s)52(FIG. 2b) and/or transformer(s)54(FIG. 2c) and/or rectifier(s)56(FIG. 2d) and/or multiplier(s)58(FIG. 2e), and the like, which condition the output electrical signal from transducers20for use in utilization device48, which may be, for example, an electrostatically aided coating material atomizer or the like. Such power conditioning equipment50may, for example, be equipment of the type illustrated and described in U.S. Pat. Nos. 4,331,298, 4,165,022, 3,731,145, 3,687,368, and/or 3,608,823.

Referring now toFIG. 3, an embodiment is illustrated in which the passageway124has a length which is tunable by moving a tuning plug160in or out in the closed end126of the passageway124. Illustratively, this is achieved by providing complementary threads on the outside of the tuning plug160and the inside of the passageway124adjacent its closed end126. A somewhat needle-like or projectile-shaped diffuser164is provided on the end face166of the tuning plug160which assists in coupling the resonant vibrations from the passageway124to the transducers120.

In yet another embodiment, illustrated inFIG. 4, the acoustic energy is channeled to the transducers220through tuned waveguides222of variable cross section. The variable cross sections of the waveguides222improve acoustic impedance matching.

In yet another embodiment, illustrated inFIG. 5, the tuning plug360and diffuser364are separated by a spring368such as, for example, a non-linear compression spring. Creation and coupling of the vibrations in the passageway324to the transducers320is thought to be aided by permitting the diffuser364to move with respect to tuning plug360. This embodiment may be useful, for example, in applications in which passageway324becomes a stagnation point. In such situations, the air temperature may tend to rise in passageway324. Such temperature changes can result in changes in the speed of sound in passageway324and the resonant frequency of passageway324. If the diffuser364containing the end wall366of passageway324is spring368—mounted and permitted to move from stagnation pressure force, the system will tend to compensate for temperature changes and resonant frequency will tend to remain constant. A non-linear compression spring, the spring constant of which takes into account the approximate variation of the speed, c, of sound with temperature T (c=√(γRT), where T is the temperature in ° K, R is the universal gas constant and γ is the ratio of the specific heats at constant pressure and constant volume, which for air is about 1.4) will tend to make the compensation more accurate.

FIGS. 6a-billustrate different cross sectional configurations for the dome-shaped flexible resonator34. InFIG. 6a, a thicker cross section of a resonator434near the center provides additional mechanical strength in the high bending moment region. This thicker section is provided by a gradual taper. In the resonator534ofFIG. 6b, this thicker section is a discrete step. These thicker cross sections near the centers of resonators434,534may be achieved by gluing or welding (an) additional member(s) or by chemical or mechanical additive or subtractive machining (for example, deposition, etching, and so on).

The first stage in the energy conversion of airflow is conversion of more well-behaved, for example, laminar or smooth, airflow into a resonating air column. Numerous mechanisms exist for doing this. One such mechanism is a knife edge resonator600. See, for example, U.S. Pat. No. 3,666,976. Another, and the one which is used in the embodiments illustrated in FIGS.1and3-5, is what is known as a Hartmann generator. See, for example, Goldman,Ultrasonic Technology, supra. Another is a Helmholtz resonator602. Another is a mechanical reed resonator604. Resonators600,602and604are illustrated highly diagrammatically inFIGS. 7a-c, respectively.

Referring toFIGS. 8-9, according to another embodiment, transducers720are arranged adjacent openings722to atmosphere around a passageway724, and not coaxially with the passageway724. The passageway724has a closed end726not terminated in a transducer720. The transducers720are attached as described above to knife edges (which are not shown, for purposes of clarity) formed at the ends of respective tubes (also not shown for purposes of clarity). The transducers720are attached, for example, by gluing with suitable adhesive(s), such as cyanoacrylate adhesive or the like, to the adjacent flat faces of respective disks736of, for example, brass or other suitable material. The apexes740of respective somewhat dome-shaped flexible resonators734are attached, for example, by gluing with suitable adhesive(s), such as cyanoacrylate adhesive or the like, to the opposite faces of respective disks736opposite the centers738of their respective transducers720.

Driving fluid, for example, a subsonic, transonic or supersonic jet of air, is directed into the open end744of passageway724, establishing the resonant column of air to drive the vibrations of transducers720which produce electrical current which is then supplied to a utilization device such as atomizer48illustrated inFIG. 2a, typically through suitable power conditioning equipment50such as, for example, (an) inverter(s)52(FIG. 2b) and/or transformer(s)54(FIG. 2c) and/or rectifier(s)56(FIG. 2d) and/or multiplier(s)58(FIG. 2e), or the like.

While the illustrated embodiments have an open end44,744and a closed end26,226,726, it is believed that passageways like passageways24,124,324,724, but with two open ends, are useful as well.