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  Thermoacoustic thermomagnetic generatorUSPTO Application #: 20070175217Title: Thermoacoustic thermomagnetic generator Abstract: The present invention is a thermoacoustic thermomagnetic generator 100. The generator includes a stator 5 that supports and channels magnetic fields. It further includes a magnetic field generator 2 that magnetically couples to the stator. In addition, the generator includes a magnetic circuit opening and closing member 1 that changes magnetic states in response to changes in temperature where the member couples to the stator to complete a magnetic circuit. Further, the generator includes a thermal insulator 4 that couples to the stator and the magnetic circuit opening and closing member. And, the generator includes a plurality of induction windings 3 that conduct electric current where the induction windings couple to the stator. The periodic opening and closing of the magnetic circuit creates a magnetic field in the stator that induces an alternating electric current in the induction windings which allows the generator to produce electric power. (end of abstract)
Agent: Matthew J. Booth & Associates, PLLC - Austin, TX, US Inventor: Oscar L. Fellows USPTO Applicaton #: 20070175217 - Class: 060645000 (USPTO) Related Patent Categories: Power Plants, Motive Fluid Energized By Externally Applied Heat, Process Of Power Production Or System Operation The Patent Description & Claims data below is from USPTO Patent Application 20070175217. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERNECE TO RELATED APPLICATIONS [0001] This application is a continuation of U.S. patent application Ser. No. 10/908,711, filed May 24, 2005, which is incorporated by reference for all purposes into this specification. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to thermoacoustic generators. More specifically, the present invention relates to thermoacoustic thermomagnetic generators. [0004] 2. Description of the Related Art [0005] The first record known of a thermo-magnetic motor making use of the Curie point property of materials is the Nikola Tesla patent, U.S. Pat. No. 396,121. In his patent, Dr. Tesla describes a kinematic thermo-magnetic motor in which a mechanism is caused to reciprocate by means of interrupting a magnetic circuit by the periodic application of heat to a metal "keeper" component that completes the magnetic circuit. The application of heat causes the keeper to transition between magnetic and non-magnetic states, and temporarily lose its ability to conduct magnetic lines of force, thereby opening the magnetic circuit. When the heat is removed the keeper cools below the Curie point transition temperature and returns to a ferromagnetic state, and the magnetic circuit is re-established. [0006] The material property that facilitates this application is known today as the Curie point of the material. It is the temperature at which a given ferromagnetic element or composition of matter, usually a metal alloy, transitions from a ferromagnetic state to an austenitic or non-magnetic state. By periodically heating and cooling the keeper and causing the keeper to periodically change states, by increasing and decreasing its temperature above and below the Curie point, Dr. Tesla created a fluctuating magnetic field that alternately attracted and released a mechanical armature and produced a reciprocating motor action. [0007] The thermomagnetic, or pyromagnetic, Curie point property of materials is also described in U.S. Pat. No. 5,714,829 by Guruprasad, which uses the property in an inverse way from this invention in that magnetic fields developing and collapsing in a pyromagnetic material also generate thermal energy, and by means of this property such alloys can be made to pump heat. In Guruprasad's invention, this effect is used for refrigeration. [0008] While ferromagnetism is generally a property of metallic materials, there are exceptions. Some organic materials such as isotopes of graphite and carbon have been known to exhibit ferromagnetic properties. Tatiana Makarova, a Russian scientist working at Umea University in Sweden, discovered that a polymerized isotope of carbon will exhibit ferromagnetic properties above room temperature. She was experimenting with buckyballs, isotopic carbon C60, searching for superconducting properties. By heating and compressing the carbon molecules, she forced them to join together in polymeric layers. To her surprise, she found that the new material was magnetic even above 200.degree. C. Prior to her discovery, the highest known temperature at which a non-metallic material was magnetic was-255.degree. C. This record was held by a different molecular form of carbon. Dr. Makarova's work is documented in the article: TATIANA L. MAKAROVA, BERTIL SUNDQVIST, ROLAND HOHN!, PABLO ESQUINAZI, YAKOV KOPELEVICH, PETER SCHARFF, VALERII A. DAVYDOV, LUDMILA S. KASHEVAROVA, ALEKSANDRA V. RAKHMANINA, "Magnetic Carbon", issue 413 of Nature, 2001, pps. 716-718. [0009] Other documented research on non-metallic magnetic materials can also be found in the article FERNANDO PALACIO, "A Magnet Made From Carbon", issue 413 of Nature, 2001, pps. 690-691, which states that experiments with nanostructured forms of graphite may have superconducting and ferromagnetic properties, also above room temperature. [0010] The NASA-Ames Laboratory also reports a rapidly expanding field within nanomagnetism called "single magnetic molecules". Their research has involved compounds synthesized as crystalline samples composed of identical molecular units. In these compounds, intramolecular magnetic interactions greatly exceed those between molecules, and macroscopic measurements reflect the magnetic properties of an individual magnetic molecule. [0011] Organic magnets could be important because they are much lighter than metals, and can also be made flexible and transparent. The study of magnetic molecules and nanoscale magnets may lead to non-metallic magnetic materials that can be used to build lighter motors and generators. [0012] It should be noted that the Neel temperature, TN, is the temperature at which a ferromagnetic or anti-ferromagnetic material becomes paramagnetic--that is, the thermal energy becomes large enough to upset the magnetic ordering within the material. This is analogous to the Curie point in ferromagnetic materials, and may be important in constructing thermomagnetic generators and refrigerators from non-metallic materials such as carbon-based materials. [0013] The present invention differs from Tesla and Guruprasad in that it applies the thermomagnetic Curie point property of materials, alternately called the thermomagnetic or pyromagnetic property, to create an induction generator with no moving parts. In the present invention, the periodic application of heat to a thermomagnetic material, preferably a metal alloy though other thermomagnetic materials could be used, in order to periodically open and close a magnetic circuit, is accomplished by means of a thermoacoustic wave train generated by a thermoacoustic engine. [0014] The operation of one example of a thermoacoustic engine is described in U.S. Pat. No. 6,385,972 (The Thermoacoustic Resonator Patent) and in U.S. Pat. No. 6,910,332 (The Thermoacoustic Engine Patent), both patents have a common inventor to the present invention. These patents describe an electromagnetic generator that is actuated dynamically by the oscillating pressure gradient in the thermoacoustic wave. In other words the armature of the generator is caused to reciprocate by the oscillating thermoacoustic wave-train, like a piston in a pneumatic motor. The present invention, however, describes a solid state, non-dynamic thermoacoustic thermomagnetic generator in which the electromagnetic field flux is caused to fluctuate, to be interrupted and re-established periodically, by the oscillating thermal gradient in the thermoacoustic wave-train. Thus, the generator of the present invention has no armature, and no moving dynamic parts. [0015] The ability of acoustic waves propagating in an elastic working fluid to transport thermal energy is well established in the physical sciences, and thermoacoustic engines and various methodologies for making them are well documented. In this instance the term "thermoacoustic" is used to describe an acoustic wave transporting thermal energy. Typically, all thermoacoustic engines have some components in common, such as an elastic working fluid, hot and cold heat exchangers, etc., though these components may differ in design and operating characteristics. By means of the present invention, the more practical form of electrical energy, derived from the less practical thermal energy, can then be used to power a wide variety of useful equipment. [0016] The present invention uses the thermal gradient in thermoacoustic waves to periodically raise the temperature of a thermomagnetic material past its Curie point so that it alternates between magnetic and non-magnetic states. In conjunction with a stator, induction windings and magnet, the metal alloy forms a magnetic circuit that is periodically interrupted and re-established by the action of the thermoacoustic waves. The expanding and collapsing magnetic field induces an alternating current in the stator windings. The resultant generator has no moving parts. This invention can be used in a thermoacoustic engine with hot and cold heat exchangers, a working fluid contained in a reservoir that is divided into hot and cold zones, and a resonant waveguide that are typical of the art of thermoacoustic engine. The basic arrangement of components of the present invention can be scaled in size from the micro-miniature to the very large. The present invention can also be arrayed in a thermoacoustic engine that contain multiple units of the present invention and includes a common waveguide, housing and hot and cold heat exchanger, such as in a panel array of multiple miniature units. SUMMARY OF THE INVENTION [0017] The present invention is a thermoacoustic thermomagnetic generator. The generator comprises a stator that supports and channels magnetic fields. It further comprises a magnetic field generator that magnetically couples to the stator. In addition, the generator includes a magnetic circuit opening and closing member that changes magnetic states in response to changes in temperature where the member couples to the stator to complete a magnetic circuit. Further, the generator includes a thermal insulator that couples to the stator and the magnetic circuit opening and closing member. And, the generator includes a plurality of induction windings that conduct electric current where the induction windings couple to the stator. The periodic opening and closing of the magnetic circuit creates a magnetic field in the stator that induces an alternating electric current in the induction windings which allows the generator to produce electric power. [0018] In addition, the magnetic circuit opening and closing member further comprises a thermomagnetic or pyromagnetic material that changes state from a ferromagnetic condition to an austenitic non-magnetic condition when its temperature is periodically increased past its Curie Point temperature by the thermal energy transported by the thermoacoustic waves impinging upon it. DESCRIPTION OF THE DRAWINGS [0019] To further aid in understanding the invention, the attached drawings help illustrate specific features of the invention and the following is a brief description of the attached drawings: [0020] FIG. 1 is a cross-sectional view of the present invention showing the component parts. Continue reading... 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