STATIC FIELD CONVERTER
U.S. Patent #5,710,531
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for producing electrical
energy and, more particularly, to an electrical device for efficiently transforming the
energy of a stationary magnetic field into useful electrical energy for use as an electric
generator, a dc/ac converter, dc transformer, or a high energy density battery through the
use of the diamagnetic properties of superconductive materials.
2. Description of the related Art
Various attempts have been made to use the Meissner effect of
superconductive materials to perform useful work. The Meissner effect occurs when a
superconductive material is cooled to a temperature below its transition point. In a
magnetic field, the lines of induction are then pushed out as if the superconductor
exhibited perfect diamagnetism. Various devices have been developed which bring a
superconductor in or out of the diamagnetic state or mechanically move a superconductive
element in relation to a magnetic field and thereby produce or control mechanical,
magnetic or electrical energy.
For example, U.S. Pat. No. 5,339,062 to Donaldson et al., issued on
Aug. 16, 1994, discloses a system where electrical energy is transferred or switched to a
secondary inductive element (a coil) through a path which contains a high temperature
superconductive element which is capable of holding off the field when in its
superconductive state. The superconductive element is driven in and out of the diamagnetic
state by heating with a laser pulse. When in its normal state, the flux passes through the
element and couples the field to the secondary, which may be connected to a load. When in
a superconductive state, there is no coupling. A primary coil of superconductive material
around the secondary coil can provide superconductive magnetic energy storage. The primary
field is held off by its superconductive elements in the flux path to opposite ends of the
secondary coil. These elements may be driven normal by laser pulses to transfer the stored
magnetic energy to a load. A plurality of secondary coils, each with associated
superconductive elements, may be selectively coupled to the load as programmed inductive
elements. Similarly, Soviet Union Patent No. 1736016-A1 dated May 23, 1992 to Kuroedov Yu
D, discloses a device for storing electromagnetic energy and generating pulsed currents
using a superconductive screen between the windings.
Japanese Patent No. 1-24474 (A) dated Jan. 26, 1989 to Sharp Corp.,
discloses a disk 11 which is driven into rotation by the repulsion between a permanent
magnet 15 and a layer of cooled superconductive material 13 at the edge of disk 11 thereby
providing rotational force. Similarly, Japanese Patent No 1-273369 (A) dated Nov. 1, 1989
to Fuji electric Co., Ltd., also uses the Meissner effect to drive a rotating disk.
Japanese Patent No. 5-268736 (A) dated Oct. 15, 1993 to Sanyo Electric Co., Ltd.,
discloses a motor driven by a dc source without energy loss. A disk is floated in position
by means of the diamagnetic properties of superconductors. Thus, the function of the
superconductive element is to suspend the rotor and eliminate friction.
Japanese Patent No. 1-149409 (A) dated Jun. 12, 1989 to Mitsubishi
Electric Corp., shows a static superconducting generator where mechanical movement of a
superconductive element in a magnetic field acts to generate power. Japanese Patent No.
1-138703 (A) dated May 31, 1989 to Toshio Takayama, discloses an electric generator using
superconductive elements as a magnetic shield. German Patent No. DE 708986 dated Mar. 19,
1987 to Priebe, K.P., shows a field effected induction unit to convert magnetic to
electric energy uses, by use of a superconducting material to form a screen of the
induction coil.
U.S. Pat. No 4,237,391 to Schur and Abolafia, discloses an electrical
generator comprising a stationary permanent magnet for establishing a magnetic field, one
or more sensing coils responsive to the magnetic field and a diamagnetic blocking element
moveable between the magnet and sensing coil for periodically interrupting the magnetic
field to produce electrical energy in the coil. In that device, the blocking element is a
rotatable disk interposed between a magnet and a coil. The rotatable disk has a
semicircular portion of magnetically inert material to alternately block and pass the
magnetic field to the coils upon rotation of the disk. It does not disclose the use of a
hemispherical shielding member which rotates around the magnetic or electromagnetic
element.
Most of these patents require bringing an element in and out of a
superconductive state and as such, require the expenditure of substantial energy in making
this transition. This prior art does not disclose a system in which a superconductive
shielding element rotates around a magnetic field to alternately expose and shield a
responsive electrical coil from the magnet.
SUMMARY OF THE INVENTION
In the present invention, a superconductive magnetic
insulating/blocking device in the form of a hemisphere, rotates inside a responsive means
such as a coil to periodically shield and unshield the responsive means from a magnetic
field. The invention provides for the efficient transformation of the energy of the
magnetic field into electrical energy and can thus be used as a dc transformer, a dc to ac
converter, an electric generator or a very high energy density battery.
Faraday's Law states the the induced emf around a closed mathematical
path in a magnetic field is equal to the rate of change of magnetic flux intercepted by
the area within the path, or
emf = -dphi/dt
emf = Electromotive Force
phi = BA
B = Magnetic Field
A = Area Bounded By Conductor
Faraday's Law is unconcerned with how the change in
magnetic flux occurs. Inefficient systems can use large amounts of energy to change the
magnetic flux and produce the electromotive force while more efficient methods for
changing the flux may be used to produce the same electromotive force for far less energy.
Thus, the efficiency in the production of the emf is a product of the efficiency in
changing the magnetic flux which passes through the closed circuit.
In the present invention, the Meissner effect of superconductive
materials (i.e., the diamagnetic properties of a superconductive material operating at a
temperature below its transition temperature) are exploited to provide a device for
producing electrical energy from a fixed magnetic field. A superconductive element
maintained at a temperature immediately below its transition temperature or colder
periodically acts to shield a responsive means such as a coil from a magnetic field
established by a permanent or electromagnet, to generate electrical energy.
A static field converter of the present invention comprises a magnetic
dipole such as a permanent or electromagnet for establishing a magnetic field, a
responsive means which generates electric current in response to the magnetic field
established by the magnetic dipole, a shielding means interposed between the field of the
magnetic dipole and a responsive means, a switching device to periodically open and close
the circuit forming the responsive means, and a driving means to rotate the shielding
means.
The magnetic dipole can be any source of magnetic field such as a
permanent or electromagnet. The shielding means comprises a magnetic flux shielding device
of diamagnetic material mounted for movement between the magnetic dipole and the
responsive means, thereby alternately shielding and unshielding the magnet flux from the
magnetic dipole to the responsive means. The shielding means of the preferred embodiment
comprises a hemisphere of superconductive material mounted such that it rotates around the
field of the magnetic dipole and the magnetic field, thereby shielding and unshielding the
responsive means from the magnetic field. The shield may form part of a rotatable sphere
composed of two hemispherical elements, the first of magnetically inert material and the
second of superconductive material. This sphere may be mounted about a sphere of
ferromagnetic material such as transformer steel or the like which would enclose and
confine the field of the magnetic dipole.
The sensing means may comprise an electrical coil positioned around the
shielding means and thus around the magnetic dipole. The coil forming the responsive means
may be periodically opened and closed during the operating cycle of the present invention
thereby eliminating magnetic resistance to rotation of the shielding means as it rotates
around the magnetic dipole and in and out of the responsive means. An electric motor or
other means can be used to rotate the shield.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other objects, features and advantages of the
present invention will become more apparent by the reading of the following description in
connection with the accompanying drawings, in which:
FIG. 1 is a perspective view, with interior elements shown by
dotted lines, of a static field converter constructed in accordance with the principles of
the present invention;
FIG. 2 is a cross-sectional view of the apparatus of FIG.1,
taken at 2-2, with lines added to show magnetic flux and other schematic elements;
FIG. 3 is a schematic diagram showing a first position of the
shield member in an operating cycle with a representation of the corresponding flux
pattern shown;
FIG. 4 is a schematic diagram showing a second position for the
shielding member in an operating cycle as it rotates 180 degrees from the first position
with the corresponding flux pattern shown; and
FIG. 5 is a schematic diagram showing the return position of the
shield member to the first position in its operating cycle with the corresponding flux
pattern shown;
FIG. 6 is a perspective view with interior elements shown by
dotted lines of a second embodiment of the static field converter constructed in
accordance with the principles of the present invention in which there are two sets of
coils.
Referring to FIGS. 1 and 2, the superconductive static
field converter unit 10 of the present invention is shown. It is adapted to be immersed in
a low temperature vessel, e.g. a Dewar tank or refrigeration unit 14 diagrammatically
shown in FIG. 2 to maintain the unit at temperatures below the transition
temperature of the superconductive material. The static field converter 10 includes a
circular base 11 provided with four support means 17, 18, 19 and 20 extending upward from
the circular base.
A magnet 13 is mounted on support means 17 and 19 by rods 15 and 16 by
conventional means such as collars 21 and 22 or alternatively a bonding method such as
adhesives (not shown) may be used. Support means 17-20, rods 15 and 16, collar 21 and 22,
and base 1 are made from non-conducting, non-ferromagnetic material such as plastic or
graphite. Magnet 13 is shown in the diagrams as an electromagnet having coils 23 around a
core 24 of transformer steel or the like. Alternatively, magnet 13 may be in the form of a
permanent magnet. Rods 15 and 16 and magnet 13 are in a fixed position and do not rotate.
The coil 12 is mounted on supports 18 and 20 by conventional means (not
shown). While responsive means 12 is shown as single coil, it may consist of several coils
either on the same or opposite hemispheres. The coil forming responsive means 12 consists
of a plurality of turns of insulated wire and includes a set of leads 26 electrically
connective to the responsive means 12 to a switch 25. Leads 27 for attachment to a
load (not shown) are connected to leads 26 through switch 25.
A shielding means 30 is rotatedly mounted on bearing 31 and 32 of a
non-conducting, non-ferromagnetic material which are rotatively position around rod 15 and
16, respectively. The shielding means 30 consists of a hemisphere of superconductive
material 35. It may be paired with a hemisphere 36 of magnetically inert material such as
Teflon to form a complete sphere for easier rotation or may consist solely of the
hemisphere of superconductive material. The field of magnet 13 is totally contained within
shielding means 30, either by the air gap between the magnet 13 and the shielding means 30
or by a ferromagnetic flux guide 45. The flux guide 45 of ferromagnetic material, such as
transformer steel, may be positioned immediately inside the shielding means 30 but not in
contact with it. The flux guide 45 completely encloses the magnet 13.
The shield is so mounted that it is freely rotated on bearings 31 and
32 around rods 15 and 16 so that the hemisphere of superconductive material can be
periodically placed between the magnet 13, its field and the responsive means 12,
thereby shielding the responsive means 12. An electric motor 40 is attached to bearing 32
through gears 41 and 42. The electric motor, when activated, rotates the shielding means
around magnet 13, alternately coming between and outside of the responsive means 12. While
an electric motor 40 is shown, other means can be used to rotate the shielding means.
In starting the apparatus, the static field converter 10 is inserted in
the refrigeration tank 14. The temperature is then reduced to below the transition
temperature of the superconductive material 35. Rotation of the shielding means 30 is
initiated by motor 40. When the switch 25 is in the open position, such that responsive
means 12 does not form a complete circuit, there is nothing to resist the rotation of the
shielding means 30 other than a normal friction encountered at bearings 31 and 32 and,
accordingly, shielding means 30 freely rotates around rods 15 and 16 as it is driven by
motor 40.
As seen in FIG. 3, at the beginning of a cycle, the
superconducting hemisphere is totally outside the coils forming responsive means 12 and
switch 25 is open circuited. Since switch 25 is open circuited, the hemisphere 35 freely
rotates up into coil 12 when driven by motor 40. Accordingly, it can freely rotate to the
position diagrammatically shown in FIG. 4 where the superconductive shielding
material is positioned totally within the coil from the responsive means 12. At this point
the responsive means 12 is completely shielded from the magnetic field and magnetic dipole
13, as diagrammatically shown in FIG. 4. At this point, switch means 25 is
automatically closed and puts a load across responsive means 12. As the shielding means 30
continues rotation, the magnetic field generated by magnet 13 is exposed to the responsive
means 12. This produces a current in the responsive means 12 and a corresponding magnetic
field. This acts to further drive the superconductive portion of the shielding means 35
around rods 15 and 16 driving it to the position shown in FIG. 5 which corresponds
to the initiating position of FIG. 3. Once it is in the position shown in FIG.
5, switch means 25 automatically opens the circuit once again so that the flux does
not generate a magnetic field in coil 12 that would repel shielding means 30.
While the invention has been disclosed with the superconductive
material being in the form of a hemisphere, it may equally be any other shape having a
cavity in which the magnet 13 can be at least partially mounted.
While the invention has been described as having a preferred design, it
is understood that it is capable of further modification, uses and/or adaptations of the
invention following in general the principal of the invention and including such
departures from the present disclosure as come with known or customary practice in the art
to which the invention pertains, as may be applied to the central figures hereinabove set
forth and fall within the scope of the invention of the limits of the appended claims.
I claim:
1. A static field converter comprising:
support means;
magnetic means for establishing a magnetic field mounted on said support means;
responsive means which is responsive to the magnetic field established by said magnetic
means mounted on the support means;
superconductive shielding means mounted on the support means, said shielding means being
movably mounted on said support means such that it can be moved around said magnetic means
and said responsive means to alternately shield and unshield the responsive means from the
magnetic field of the magnetic means;
switching means connected to said responsive means which can be opened and closed as the
shielding means connected to said responsive means which can be opened and closed as the
shielding means moves around the magnetic field produced by the magnetic means; and
the magnetic means is positioned at least partially within the responsive means.
2. A field converter according to claim 1, where the shielding
means consists of a hemisphere of superconductive material which is rotatably mounted on
the support means between the magnetic means and the responsive means such that the
shielding means rotates around the magnetic means, periodically shielding and unshielding
the responsive means from the magnetic flux of the magnetic means.
3. A field converter according to claim 2, wherein there is a
flux guide of ferromagnetic material positioned between the magnetic means and the
shielding means which completely encloses the magnetic means.
4. A field converter according to claim 2, wherein the shielding
means has a non-superconductive hemisphere opposite the hemisphere of superconductive
material to form a single sphere containing superconductive and non-superconductive
portions in which the magnetic means is mounted.
5. A field converter according to claim 2 wherein there is a
cooling means for maintaining the shielding means below the transition temperature of the
superconductive material from which it is formed.
6. The static field converter of claim 2, where at least two
responsive means are mounted on either end of the magnetic dipole.
7. The static field converter of claim 6, where each of the
responsive means consists of a coil of electrically conductive, insulated wire wound in
the form of a cylinder larger in diameter than the diameter of the superconductive
hemisphere of the shielding means, positioned such that when the hemisphere of the
shielding means is fully rotated into one of said responsive means, it completely
surrounds the portion of the magnetic means positioned in said responsive means.
8. A field converter according to claim 1, wherein a driving
means rotates the shielding means around the magnetic means.
9. A field converter according to claim 1, where the shielding
means consists of a superconductive material which is rotatably mounted on the support
means between magnetic means and the responsive means and where the shielding means has a
cavity in which the magnetic means is at least partially mounted such that the shielding
means rotates around the magnetic means, periodically shielding and unshielding the
responsive means from the magnetic flux of the magnetic means.
10. A field converter according to claim 9, wherein the
shielding means has a non-superconductive element opposite the superconductive element to
form a single body containing superconductive and non-superconductive portions in which
the magnetic means is mounted.
11. A field converter according to claim 9, wherein there is a
cooling means for maintaining the shielding means below the transition temperature of the
superconductive material from which it is formed.
12. The static field converter of claim 9, where at least two
responsive means are mounted on either end of the magnetic dipole.
13. The static field converter of claim 12, where each of the
responsive means consists of a coil of electrically conductive, insulated wire wound in
the form of a cylinder larger in diameter than the diameter of the superconductive
shielding means, positioned such that when the shielding means is fully rotated into one
of said responsive means, it completely surrounds the portion of the magnetic means
positioned in said responsive means.
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Analysis of a Practical Embodiment of the Patent