Note: Descriptions are shown in the official language in which they were submitted.
CA 02532507 2006-01-09
CONTROLLED MAGNETIC HEAT GENERATION
Field of the Invention
The present invention is related to devices for the production of heat, and
more
particularly, to methods and apparatus for generating heat using magnetic
induction.
Background
A magnetic heater generates heat by a phenomenon known as magnetic inductive
heating. Magnetic inductive heating occurs in an electrically conductive
member when
exposed to a time-varying magnetic field. The varying magnetic field induces
eddy
currents within the conductive member, thereby heating it. An increase in the
magnitude
of the variations of the magnetic field increases the rate at which the
conductive member
is heated. The heated conductive member can then be used as a heat source for
various
purposes. The heated conductive member is often used to heat a fluid, such as
air or
water, that is circulated past the conductive member. The heated fluid is then
used to
transfer the heat from the heater for external use.
One method of exposing a conductive member to a varying magnetic field is to
move a magnetic field source relative to the conductive member. This motion
may be
achieved by arranging magnets around the edge of a circular disk having a
rotatable shaft
substantially at its center, the flat surface of the disk being opposable to
an essentially flat
portion of the surface of the conductive member. As the shaft of the disk is
rotated, the
magnets move relative to the surface of the conductive member. A given point
on the
conductive member is exposed to a cyclically varying magnetic field as each of
the
magnets approach, pass over, and retreat from that given point.
The amount of heat induced within the conductive member depends on many
factors, some of which include the strength of the magnetic field, the
distance between
the magnets and the conductive member (referred herein as the
"conductor/magnet
spacing"), and the relative speed of the magnets to the conductive member.
Conventional magnetic heaters suffer from several disadvantages. For example,
many conventional magnetic heaters have limited precision in their control of
operational
parameters such as the rate of heat generation, the flow rate of a working
fluid used to
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carry heat, and the temperature of that working fluid. In particular, it is
difficult to control
these and other operational parameters independently from one another with
conventional
magnetic heaters.
For a given conductor/magnet spacing and a given magnetic field strength,
increasing the disk rotation speed increases the rate of cyclical variation of
the magnetic
field at a given point on the conductive member, thus increasing the heating
of the
conductive member. Therefore, in order to be able to vary the heating of the
conductive
member, and thus have a range of heat output from the heater, the rotation
speed of the
disk must be variably controlled. For example, if a motor is used as the
energy source
driving the shaft to rotate the disk, the motor speed must be variable in
order to vary the
heating of the conductive member. If a windmill is used as an energy source,
it may be
very difficult to selectively change the rotation speed of the disk.
In order to produce a constant heat output from the heater, a constant
rotation
speed of the disk must be maintained. If an internal combustion engine is used
as the
energy source driving the shaft to rotate the disk, the engine must be
throttleable to
produce a constant output at a given tachometer setting, in order to induce a
constant
heating of the conductive member. A power takeoff from a vehicle engine, such
as a
tractor engine, commonly has a constant speed of rotation for a given throttle
setting.
Although it is possible to change the heat output by varying the engine speed,
doing so
may effect the vehicle in undesirable ways. If a windmill is used as an energy
source to
rotate the disk, it is very difficult to produce a constant rotation speed of
the disk.
Some magnetic heaters utilize a rotating disk designed with a preferential
shape to
provide the driving force for circulating heat-transfer fluid. Alternatively,
the shaft is
used to drive a fluid pump. Consequently, the fluid flow rate is directly
determined by
the rotation speed of the shaft. Driving the fluid in this manner makes it
difficult to
control the temperature of the fluid exiting the magnetic heater. As the shaft
speed is
increased in order to increase the heating of the conductive member, the flow
rate of the
fluid is consequently also increased, which, in-turn, works against obtaining
a desired
fluid temperature for a given flow rate.
Although it is possible to address the difficulty of controlling fluid flow
and/or
fluid temperature by driving the fluid with a mechanism separate from that
used to rotate
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the disk, reliance on such an additional mechanism tends to increase the size,
weight, and
complexity of the magnetic heater.
The disadvantages of limited control of operational parameters impact the
usefulness of the magnetic heater. For example, many types of grain are
routinely dried
after harvesting by exposure to a flow of heated air. The appropriate
temperature to which
the air should be heated and the preferred rate of air flow depend on many
variables, such
as the amount of moisture in the grain, the type of grain being dried, and the
quantity of
grain present. A conventional magnetic heater that cannot reliably maintain
operating
parameters at their desired levels, or that cannot readily be adjusted to
reach those desired
levels, is of limited use in drying the grain.
Therefore, a magnetic heater is needed that facilitates control over various
parameters, in combination or individually.
Summary
In an embodiment in accordance with the present invention, a magnetic heater
comprises a conductive member having a conductive member first side and a
conductive
member second side, and a first magnet assembly comprising a first frame and
at least
one magnet movably coupled to the first frame, the at least one magnet
disposed a first
distance adjacent the conductive member first side, wherein the conductive
member and
the first magnet assembly are adapted to rotate relative to each other about
an axis so as
to induce eddy currents in the conductive member when relative motion is
produced
between the conductive member and the first magnet assembly, the at least one
magnet
adapted to move relative to the first frame in dependence on the change in the
rate of
rotation of the first frame.
In another embodiment in accordance with the present invention, the first
magnet
assembly further comprises at least one passive relative-positioning actuator
adapted to
move one or more magnets in at least one of an axial direction and a radial
direction
relative to the frame.
In another embodiment in accordance with the present invention, the first
frame
further comprises a linkage guide, the passive relative-positioning actuator
comprising a
pivot mount adapted to couple with one or more magnets, a bias member having a
bias
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member first end and a bias member second end, a first linkage arm having a
first
linkage-arm first-end pivotally coupled to the frame distal from the axis and
a first
linkage-arm second-end pivotally coupled to the pivot mount, a second linkage
arm
having a second linkage-arm first-end coupled in sliding and pivoting
engagement with
the linkage guide and coupled to the bias member second end, and a second
linkage-arm
second-end pivotally coupled to the pivot mount, the linkage guide adapted to
guide and
restrict the second linkage-arm second-end to movement in a substantially
radial
direction, the bias member first end coupled to the frame preferentially
positioned to
apply bias when the bias member second-end is moved in a radial direction away
from
the axis, wherein the pivot mount moves relative to the frame when the frame
is rotated at
a changing rate of rotation.
In another embodiment in accordance with the present invention, the frame
further comprises a linkage guide, and the passive relative-positioning
actuator comprises
a pivot mount adapted to couple with one or more magnets, a bias member having
a bias
member first end and a bias member second end, a first linkage arm having a
first
linkage-arm first-end coupled in sliding and pivoting engagement with the
linkage guide
and coupled to the bias member second end, and a first linkage-arm second-end
pivotally
coupled to the pivot mount, a second linkage arm having a second linkage-arm
first-end
pivotally coupled to the frame proximate to the axis, and a second linkage-arm
second-
end pivotally coupled to the pivot mount, the linkage guide adapted to guide
and restrict
the first linkage-arm first-end to movement in a substantially radial
direction, the bias
member first end coupled to the frame preferentially positioned to apply bias
when the
bias member second-end is moved in a radial direction away from the axis,
wherein the
pivot mount moves relative to the first frame when the first frame is rotated
at a changing
rate of rotation.
In another embodiment in accordance with the present invention, the passive
relative-positioning actuator comprises a pivot mount adapted to couple with
one or more
magnets, a bias member having a bias member first end and a bias member second
end, a
pivot arm having a pivot-arm first-end coupled in pivoting engagement with the
first
frame distal from the axis, and a pivot-arm second-end pivotally coupled to
the pivot
mount and coupled to the bias member second end, the bias member first end
coupled to
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the frame preferentially positioned to apply bias when the bias member second-
end is
moved in a radial direction away from the axis, wherein the pivot mount moves
relative
to the first frame when the first frame is rotated at a changing rate of
rotation.
In another embodiment in accordance with the present invention, the passive
relative-positioning actuator comprises a bimetallic spring, wherein the first
frame
comprises one or more slots, each defining an axial-facing tang, the tang
adapted to
couple with at least one magnet, the tang comprising a first material having a
first
coefficient of thermal expansion and a second material having a second
coefficient of
thermal expansion to form a bimetallic spring, wherein as the temperature of
the
bimetallic spring rises, the bimetallic spring causes the tang to deflect in a
preferred
direction relative to the conductive member.
In another embodiment in accordance with the present invention, the first
frame
further comprises a pin guide, and the passive relative-positioning actuator
comprises a
mount adapted to couple with one or more magnets, a guide pin coupled to the
mount,
and a bias member having a bias member first-end and a bias member second-end,
the
pin guide adapted to slidingly receive the guide pin and restrict movement of
the guide
pin to a substantially radial direction, the bias member first-end is coupled
to the frame
proximate the axis, and the bias member second-end is coupled to the mount.
In another embodiment in accordance with the present invention, the conductive
member is disc shaped.
In another embodiment in accordance with the present invention, the conductive
member comprises a substantially disc-shaped center portion and a plurality of
arms
extending from the center portion.
In another embodiment in accordance with the present invention, the conductive
member comprises a plurality of conductive portions separated by non-
conductive
portions.
In another embodiment in accordance with the present invention, the conductive
member comprises a plurality of nested rings separated by non-conductive
portions.
In another embodiment in accordance with the present invention, the magnetic
heater further comprises a second magnet assembly comprising a second frame
and at
least one magnet movably coupled to the second frame, the at least one magnet
disposed
CA 02532507 2006-01-09
a second distance adjacent the conductive member first side, wherein the
second magnet
assembly and the second frame are adapted to rotate relative to each other
about an axis
so as to induce eddy currents in the conductive member when relative motion is
produced
between the second magnet assembly and the second frame, the at least one
magnet
adapted to move relative to the second frame in dependence with the rate of
rotation of
the second frame.
In another embodiment in accordance with the present invention, a magnetic
heater comprises a magnet assembly having a magnet assembly first side and a
magnet
assembly second side, the magnet assembly comprising at least one magnet, and
a first
conductive member assembly comprising a first frame and at least one conductor
movably coupled to the first frame, the at least one conductor disposed a
first distance
adjacent the magnetic assembly first side, wherein the first conductive member
assembly
and the first frame are adapted to rotate relative to each other about an axis
so as to
induce eddy currents in the at least one conductor when relative motion is
produced
between the magnet assembly and the first frame, the at least one conductor
adapted to
move relative to the first frame in dependence with the rate of rotation of
the first frame.
In another embodiment in accordance with the present invention, the first
conductive member assembly further comprises at least one passive relative-
positioning
actuator adapted to move one or more conductors in at least one of an axial
direction and
a radial direction relative to the frame.
In another embodiment in accordance with the present invention, a method of
generating heat comprises disposing at least one magnet on a first and second
frame
proximate each of a first and second side, respectively, of at least one
conductive
member, cyclically varying a magnetic field applied by the at least one magnet
on at least
a portion of the conductive member so as to heat the conductive member
thereby, and
passively adjusting a rate of heat generation in the conductive member while
the
conductive member is being heated by the at least one magnet, wherein each of
the at
least one magnet is adapted to move relative to the first and second frame in
dependence
on the rate of rotation of the first and second frame.
In another embodiment in accordance with the present invention, a magnetic
heater apparatus comprises a rear housing, a first end plate, a heater
housing, a magnetic
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heater, a second end plate, and a blower housing. The magnetic heater
comprises a shaft,
a first magnet assembly, a conductive member, a second magnet assembly, and a
fluid
driver. The first and second magnet assemblies have a plurality of magnets,
the
conductive member disposed between and coaxial with the first and second
magnet
assemblies, the conductive member coupled with the shaft and adapted to rotate
with
respect to the first and second magnet assemblies, the shaft adapted to couple
with an
energy source, the rear housing coupled adjacent the first end plate and
comprising
apertures adapted to accept the shaft therethrough, the first end plate
coupled adjacent the
heater housing defining a volume adapted to contain the first and second
magnet
assemblies and conductive member, the second end plate coupled adjacent the
heater
housing defining a side of the volume, the heater housing comprises a fluid
outlet, the
second end plate comprises a second end plate aperture defining a portion of a
fluid path,
the fluid driver coupled to the shaft and located adjacent the second end
panel on the
opposite side from the second magnet assembly, the blower housing coupled
adjacent the
second end panel adapted to enclose the fluid driver therebetween, the blower
housing
defining a fluid inlet aperture defining a portion of the fluid path, the
fluid path defined
by the fluid inlet aperture, the fluid driver, the second end plate aperture,
the heater
housing and the fluid outlet.
In another embodiment in accordance with the present invention, the magnetic
heater apparatus further comprises a spacing adjustment assembly comprising a
knob, a
threaded spacer having a first spacer end and a second spacer end, a first
retention
coupler, and a second retention coupler, the first retention coupler disposed
adjacent the
first magnet assembly and the second retention coupler disposed adjacent the
second
magnet assembly, the threaded spacer disposed between the first and second
magnet
assemblies, the first spacer end coupled with the first retention coupler, the
second spacer
end disposed through the second retention coupler and coupled to the knob,
wherein
turning the knob in a first direction reduces the spacing between the first
and second
magnet assemblies and turning the knob in an opposite direction increases the
spacing
between the first and second magnet assemblies.
In another embodiment in accordance with the present invention, the first and
second magnet assemblies further comprise a frame, and at least one passive
relative-
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positioning actuator adapted to move one or more magnets in at least one of an
axial
direction and a radial direction relative to the frame, wherein the relative
motion is
produced in dependence on the change in the rate of rotation of the frame.
Brief Description of the Drawings
Like reference numbers generally indicate corresponding elements in the
figures.
Figure 1 is a side view of an embodiment of a magnetic heater, in accordance
with
an embodiment of the present invention;
Figure 2 is a front view of the magnet assembly of Figure 1;
Figure 3 is a side view of a magnetic heater, in accordance with an embodiment
of
the present invention;
Figure 4 is a front view of a conductive member comprising a plurality of
separate
conductors, in accordance with an embodiment of the present invention;
Figure 5 is a portion of the frame with a cross-sectional view of a magnet and
a
protective layer provided on the exterior of the magnet, in accordance with an
embodiment of the present invention;
Figure 6 is a side view of an embodiment of a magnetic heater, in accordance
with
an embodiment of the present invention;
Figure 7 is a side view of a magnetic heater, in accordance with an embodiment
of
the present invention;
Figure 8 is a front view of the embodiment of Figure 7;
Figures 9A and 9B are side views of the magnetic heater comprising a spacing
actuator for varying the conductor/magnet spacing, in accordance with an
embodiment of
the present invention;
Figure 10A is a side view of a rotatable magnet assembly comprising a linkage-
arm apparatus, in accordance with an embodiment of the present invention;
Figure l OB is a side view of a conductive member assembly comprising a
linkage-arm apparatus, in accordance with an embodiment of the present
invention.
Figure 11 is a side view of a rotatable magnet assembly comprising a linkage-
arm
apparatus, in accordance with an embodiment of the present invention;
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Figure 12 is a side view of a rotatable magnet assembly comprising a linkage-
arm
apparatus, in accordance with an embodiment of the present invention;
Figure 13 is a side view of a rotatable magnet assembly comprising a linkage-
arm
apparatus, in accordance with an embodiment of the present invention;
Figures 14A and 14B are front and side views of a bimetallic spring frame
comprising one or more slots defining an axial-facing tang assembly, in
accordance with
an embodiment of the present invention;
Figure 15A and 15B are side and front views of a rotatable magnet assembly, in
accordance with an embodiment of the present invention;
Figure 16A is a front view of a radially moving magnet relative to a
conductive
member, in accordance with an embodiment of the present invention;
Figure 16B is a graph showing a temperature curve illustrating the trend in
the
temperature generated in the conductive member with the change in radial
position of the
magnet, in accordance with an embodiment of the present invention;
Figure 17A is a front view of a radially moving magnet relative to a
conductive
member, in accordance with an embodiment of the present invention;
Figure 17B is a graph showing a temperature curve illustrating the trend in
the
temperature generated in the conductive member with the change in radial
position of the
magnet, in accordance with an embodiment of the present invention;
Figure 18A is a front view of a radially moving magnet relative to a
conductive
member comprising a plurality of individual rings, in accordance with an
embodiment of
the present invention;
Figure 18B is a graph showing a temperature curve illustrating the trend in
the
temperature generated in the conductive member with the change in radial
position of the
magnet, in accordance with an embodiment of the present invention;
Figure 19 is a side view of a radially moving magnet relative to a conductive
member, in accordance with an embodiment of the present invention;
Figure 20 is a partial view of the embodiment of Figure 19, wherein different
polarities of opposing magnets face the conductive member, in accordance with
an
embodiment of the present invention;
Figure 21 is a multi-stage magnetic heater, in accordance with an embodiment
of
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the present invention;
Figure 22 is a perspective view of a magnetic heater apparatus, in accordance
with
an embodiment of the present invention; and
Figure 23 is an exploded view of the magnetic heater apparatus of Figure 22.
Detailed Description
Figure 1 is a side view of an embodiment of a magnetic heater 2 in accordance
with an embodiment of the present invention. The magnetic heater 2 comprises a
magnet
assembly 20 and a conductive member 14 disposed proximate the magnet assembly
20.
Rotation of the magnet assembly 20 about an x-axis induces a predetermined
cyclical
variation of magnetic field within the conductive member 14.
Figure 2 is a front view of the magnet assembly 20. The magnet assembly 20
comprises a disk-shaped frame 22, a plurality of magnets 12, and a shaft 18.
The
plurality of magnets 12 are coupled to and arranged in a planar, generally
circular,
spaced-apart, orientation on the frame 22. The magnets 12 each have a first
magnet
surface 13 in a substantially planar relationship, referred herein as the
first magnet plane
21, shown in Figure 1. The shaft 18 is coupled substantially at the center of
rotation of
the frame 22. The center of rotation of the frame 22 defines the x-axis which
is
substantially perpendicular to the first magnet plane 21. The shaft 18 is
adapted to couple
with an energy source capable of imparting rotation to the shaft 18.
The conductive member 14 has a planar conductive member first side 15 in
opposing, substantially parallel relationship with the first magnet plane 21.
The
conductive member first side 15 and the first magnetic plane 21 are in spaced-
apart
opposing relationship a predetermined distance referred herein as a
conductor/magnet
spacing X1.
As the shaft 18 of the frame 22 is rotated, the magnets 12 move relative to
the
conductive member first side 15 of the conductive member 14. A given point on
the
conductive member 14 will, therefore, be exposed to a cyclically varying
magnetic field
as each of the magnets 12 approach, pass over, and retreat from adjacent that
given point.
The given point on the conductive member 14 will thus be heated as long as the
given
point is exposed to the time-varying magnetic field.
CA 02532507 2006-01-09
It is appreciated that the magnet assembly 20 can comprise one or more magnets
12. One magnet 12 is sufficient to expose a cyclically varying magnetic field
onto the
conductive member 14. Therefore, it is appreciated that when reference is made
to a
plurality of magnets 12, it applies also to embodiments comprising one magnet
12, and
vice-versa.
In embodiments of the present invention, the magnets 12 are permanent magnets.
Therefore, the magnets 12 have a substantially constant magnetic field
strength. This is
contrasted with an electromagnet, which has the capability of producing a
range of
magnetic field strength dependent on varying the current driving the
electromagnet.
Therefore, the strength of the magnetic field produced by the permanent
magnets 12 that
the conductive member is exposed to primarily depends on the conductor/magnet
spacing
Xl. The magnetic field strength of the permanent magnet 12 is referred to as
the absolute
magnetic field strength.
A fluid path 16 is defined such that heat transfer between the conductive
member
14 and fluid moving within the fluid path 16 is enabled. Thus, as the
conductive member
14 is heated, the fluid absorbs at least a portion of the heat generated. The
fluid can thus
be used to transport the heat to another location.
The radial and axial placement of the magnets 12 about the frame 22 as shown
in
Figures 1 and 2 is exemplary only. Placement of the magnets 12 about the frame
22 in
other arrangements, orientations, spacing, among other things, in planar
relationship or
otherwise, is anticipated suitable for a particular purpose of imparting a
magnetic field
onto the conductive member 14 and/or onto additional conductive members.
Furthermore, the magnets 12 need not be of the same size, shape, polar
orientation,
composition, or type, another other things.
In the embodiment of Figures 1 and 2, the magnets 12 are oriented such that
the
conductive member 14 is exposed to an alternating polarity from adjacent
magnets 12,
with their north poles N either pointing towards or away from the conductive
member 14.
Such an arrangement produces a relatively large range of variation in the
magnetic field
on the conductive member 14 as compared with, for example, wherein all of the
magnets
12 present the same polarity to the conductive member 14.
Relative motion between the conductive member 14 and the magnets 12 is
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produced, wherein the magnets 12, are caused to rotate about the x-axis and
holding the
conductive member 14 stationary.
Figure 3 is a side view of a magnetic heater 3 wherein the conductive member
14
is caused to rotate about the x-axis and holding the magnets 12 stationary.
The
conductive member is coupled to a shaft 18 that is coupled to an energy source
suitable
for rotating the shaft 18 about the x-axis.
It is understood that relative motion between the magnets 12 and the
conductive
member 14 can be produced, in accordance with embodiments of the present
invention,
by the above mentioned configurations, and by other configurations, such as,
but not
limited to, rotation of both magnets 12 and conductive member 14 at different
rates in the
same direction, and rotation of both magnets 12 and conductive member 14 in
opposite
directions.
The absolute magnetic field strength of the magnet 12 is a measure of the
magnitude of the magnetic field generated by the magnet 12 at a point on the
magnet. For
permanent magnets, the absolute magnetic field strength is essentially fixed.
For
electromagnets, the absolute magnetic field strength depends on the amount of
current
passing through the magnets coils.
The magnetic field exerted on the conductive member 14 depends on, among
other things, the absolute magnetic field strength of the magnet 12 and the
conductor/magnet spacing Xl between the magnet 12 and the conductive member
14.
A variety of magnets 12 are suitable for embodiments of the present invention.
Permanent magnets 12 are advantageous for certain embodiments, for at least
the reason
that it is not necessary to supply electrical power to the magnets 12, hence
no wiring or
power source is needed for such purpose.
The rate of heat generation in a magnetic heater 2, 3 in accordance with
embodiments of the present invention depends in part on the absolute magnetic
field
strength of the magnets 12. Therefore, for applications wherein a high rate of
heat
generation is desirable, it is also desirable that the magnets 12 have a
relatively high
absolute magnetic field strength.
In addition, the maximum temperature that can be generated by a magnetic
heater
2, 3 according to the embodiments of the present invention depends in part on
the heat
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tolerance of the magnets 12. Permanent magnets have a "maximum effective
operating
temperature" above which their magnetic field begins to degrade significantly.
Electromagnets likewise suffer from decreased performance with increasing
temperature, though the decrease is not as well defined as that of permanent
magnets. For
example, the resistance of the magnetic field coils in an electromagnet
gradually
increases with increasing temperature, which in turn gradually reduces the
current flow at
a given voltage, generating still more heat. Magnets of both types are
available suitable
for use at elevated temperatures.
Permanent magnets known as rare earth magnets, such as, but not limited to
Samarium Cobalt magnets, have a relative high absolute magnetic field strength
and
operating temperature, and are suitable for the particular purpose.
The conductive member 14 comprises an electrically conductive material
suitable
for the particular purpose. Suitable materials include, but are not limited
to, copper,
aluminum, alloys of copper, alloys of aluminum, and other metallic or non-
metallic,
electrically conductive substances. The conductive member 14 of the embodiment
of
Figure 1 is generally disc-shaped. The conductive member 14 is not
particularly limited
to a specific shape, size, or configuration. In other embodiments, the
conductive member
is formed in two or more pieces, as a thin conductive layer on a non-
conductive substrate,
having define apertures therein, among other configurations.
The conductive member 14 need not consist of a closed loop or integral piece
of
conductive material. Figure 4 is a front view of a conductive member 14
comprising a
plurality of separate conductors 27 that are separated from one another by non-
conductive
material 48 in accordance with an embodiment of the present invention. In such
a case,
each conductor 27 is heated independently.
Likewise, the conductive member 14, even if a single contiguous piece of
conductive material, might be shaped with apertures, or be constructed of
wires, beams,
rods, etc., with empty space therebetween.
Figures 1 through 3 show the magnetic heater 2, 3 in simplified schematic form
for clarity. It is understood that additional structure may be present to
provide structural
support for containment and alignment. Figure 5 is a portion of the frame 22
with a cross-
sectional view of a magnet 12 and a protective layer 31 provided on the
exterior of the
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magnet 12. The protective layer 31 is selected for a particular purpose,
including, but not
limited to, thermal protection, additional structural integrity, and chemical
protection.
A variety of materials are suitable for use as the protective layer 31, so
long as
they do not significantly reduce the propagation of the magnetic field of the
magnet 12.
In one embodiment, the protective layer 31 comprises aluminum. It is noted
that
aluminum has a high reflectivity, thus inhibiting the absorption of heat by
the magnet 12,
and a high infrared emissivity, thus facilitating the rapid re-radiation of
heat away from
the magnet 12. These properties combine to provide passive cooling for the
magnet 12. In
addition, aluminum is relatively durable, and so a protective layer 31 of
aluminum serves
to protect the magnet 12 physically. Likewise, aluminum is relatively
impermeable, and
thus may effectively seal the magnet 12 against any potential corrosive
effects due to
moisture, oxygen, fluid flowing through the fluid path 16 (see below), among
other
things.
In addition, for certain embodiments, the magnetic heater may include an
additional active or passive cooling mechanism for the magnets 12. A wide
variety of
cooling mechanisms are suitable for the particular purpose. For example,
passive cooling
mechanisms include, but are not limited to, heat sinks and radiator fins.
Active cooling
mechanisms include, but are not limited to, coolant loops and refrigeration
units.
It is noted that the fluid flow path 16, as described below, may be configured
to
act as a cooling mechanism. Embodiments of the present invention use fluid to
provide a
mechanism for absorbing heat from the conductive member 22, and it is well
suited for
absorbing heat from the magnets 12 as well.
In embodiments in accordance with the present invention, heat is generated for
use via direct conduction or radiation from the conductive member 22. For
example, heat
could be transferred from the conductive member 14 to a solid heat conductor,
heat sink,
or heat storage device, such as, but not limited to, a mass of ceramic, brick,
stone, etc.
Figure 6 is a side view of the magnetic heater 2 wherein the fluid path 16 is
defined so that at least a portion thereof extends between the magnets 12 and
the
conductive member 14 in accordance with embodiments of the present invention.
The
fluid path 16 extends substantially parallel with the conductive member 14 and
the
magnets 12, between the magnets 12 and the conductive member 14.
14
CA 02532507 2006-01-09
Suitable fluids for the particular purpose include, but are not limited to,
gaseous
fluids such as air and liquid fluids such as water. When the conductive member
22 is
heated, fluid in the fluid path 16 receives heat from conductive member 22.
Heat transfer
from the conductive member 22 to fluid in the fluid path 16 may occur via one
or more of
conduction, convection, and radiation.
Figures 7 and 8 are side and front views of an embodiment of the magnetic
heater
2 further comprising a fluid driver 34 engaged with a fluid path 16 for
driving fluid
therethrough. The fluid driver 34 comprises a plurality of fins 35 or blades
and a driver
shaft 36. Examples of suitable fluid drivers 34 include, but are not limited
to, finned
rotors, squirrel cages, and fans. In the embodiment of Figure 7, the driver
shaft 36
extends through an aperture 37 in the conductive member 14 and is coupled to
the frame
22 on which the magnets 12 are arranged. The driving action is provided by
rotation of
the frame 22, which turns the fluid driver 34 in a predetermined direction.
Thus, the
speed of operation of the fluid driver 34 therein depends on the speed of
motion of the
frame 22, and likewise the rate of fluid flow within the fluid path 16. In
other
embodiments, the driver shaft 36 is coupled to, among other things, the shaft
18 or an
external energy source.
In an embodiment wherein the conductive member 14 rather than the frame 22
moves to produce the cyclically varying magnetic field, the fluid driver 34 is
driven by
the rotation of the conductive member 14.
It is appreciated that the temperature to which fluid passing through the
fluid path
16 is heated depends on the rate of heat generation in the conductive member
14, that is,
on the amount of heat available to warm the fluid. Also, the temperature of
the fluid
depends on the rate at which the fluid moves through the fluid path 16, that
is, on how
much fluid is available to absorb the heat that is generated.
Also because the parameters, including rate of heat generation, rate of fluid
flow,
and fluid temperature, are independent of one another as described in some
embodiments
herein, a magnetic heater 2 in accordance with embodiments of the present
invention is
used to produce a specific temperature of fluid in combination with a specific
quantity of
fluid flow. Any two of the three parameters can be controlled independently of
one
another.
CA 02532507 2006-01-09
The energy source used to drive the shaft 18 can comprise any suitable means.
In embodiments in accordance with the present invention, the shaft 18 is
coupled
with a power take-off found on some vehicles, such as, but not limited to,
many tractors,
other agricultural vehicles, and heavy work vehicles. In such vehicles, some
or all of the
mechanical driving force generated by the engine is transferred to the power
take-off to
impart rotation, such as to the shaft 18. Conventional power take-offs include
a rotatable
coupling or other movable component, which is engaged with a linkage to impart
rotation
to the shaft 18.
In other embodiments, the shaft 18 comprises a hydraulic linkage. Certain
vehicles include hydraulic systems, such as, but not limited to, for actuating
a snow plow
or shovel blade, for tipping a truck bed, or for operating a fork lift. The
hydraulic system
is adapted to couple with a piece of supplemental equipment, such as a
hydraulic motor,
with suitable linkage adapted to couple with the shaft 18, to provide power
thereto.
Hydraulic systems and hydraulic linkages are known in the art, and are not
described in
detail herein.
Various embodiments are anticipated so as to control the rate of heat output
of the
magnetic heater 2.
Figures 9A and 9B are side views of the magnetic heater 2 of Figure 1, further
comprising a spacing actuator 26 for varying the conductor/magnet spacing X1,
in
accordance with an embodiment of the present invention. The spacing actuator
26 varies
the conductor/magnet spacing Xl between the conductive member first side 15
and the
first magnet surface 13 along the x-axis.
The strength of the magnetic field exerted on a given portion of the
conductive
member 14 depends in part on the conductor/magnet spacing X1 between the
magnets 12
and the conductive member 14. A change in the conductor/magnet spacing Xl
changes
the magnetic field strength to which the conductive member 14 is exposed, and
thus
changes the range of variation of the magnetic field over a cycle (the
cyclical variation of
the magnetic field), which changes the rate at which heat is generated in the
conductive
member 14. For permanent magnets, the cyclical variation of the magnetic field
is
accomplished while the absolute magnitude of the magnetic field strength
remains
substantially constant.
16
CA 02532507 2006-01-09
Reducing the conductor/magnet spacing X1 increases the magnetic field strength
on the conductive member 14 and increases the magnetic induction, thus
increasing the
heating of the conductive member 14. Increasing the conductor/magnet spacing
Xl
reduces the magnetic field strength on the conductive member 14 and reduces
the
magnetic induction, thus reducing the heating of the conductive member 14.
In embodiments wherein it is desirable to enable a relatively high maximum
rate
of heat generation, it is desirable that a minimum value of the
conductor/magnet spacing
X1 between the conductive member 14 and the magnets 12 be as small as is
practical.
Similarly, in embodiments wherein it is desirable to enable a high range of
variability in
the rate of heat generation, it is desirable that the range of possible values
for the
conductor/magnet spacing X1 between the conductive member 14 and the magnets
12 is
relatively large.
The conductor/magnet spacing X1 is a parameter that is independent of the rate
of
motion of the magnets 12 with respect to the conductive member 14, and thus
independent of the rate of cyclical variation of the magnetic field. Thus, the
rate of heat
generation of the magnetic heater 2 is adjustable by varying the
conductor/magnet
spacing X1 without changing the period of cyclical variation of the magnet
magnetic
field.
Likewise, the conductor/magnet spacing Xl is independent of the absolute
magnetic field strength of the magnets 12. Thus, the rate of heat generation
of the
magnetic heater 2 is adjustable by varying the conductor/magnet spacing X1
without
changing the absolute magnetic field strength of the magnets 12. What is
changing with
varying the conductor/magnet spacing Xl, among other things, is the magnitude
of the
magnetic field that the conductive member 14 is exposed to. The rate of heat
generation
of the magnetic heater 2 is adjustable while it is generating heat by
adjusting the
conductor/magnet spacing X1.
The spacing actuator 26 is engaged with either the magnet assembly 20 or the
conductive member 14 so as to vary the conductor/magnet spacing Xl
therebetween. In
other embodiments, the magnetic heater 2 comprises separate spacing actuators
26
engaged with the magnet assembly 20 and the conductive member 14. Such
arrangements
facilitates adjustment of the conductor/magnet spacing X1, and consequently
facilitates
17
CA 02532507 2006-01-09
adjustment of the rate of heat generation. In an embodiment in accordance with
the
present invention, the spacing actuator 26 is used to facilitate adjustment of
the
conductor/magnet spacing X1 while the magnetic heater 2 is generating heat.
A variety of actuators are suitable for use as the spacing actuator 26. In one
embodiment, as schematically illustrated in Figures 9A and 9B, the spacing
actuator 26 is
a simple linear actuator, engaged with the conductive member 14 to move it
toward or
away from the magnet assembly 20, thereby adjusting the conductor/magnet
spacing
from X1 to X2.
In an embodiment in accordance with the present invention, the spacing
actuator
26 is a manual actuator, such as, but not limited to, a threaded screw
controlled by a
hand-turned knob. In other embodiments, the spacing actuator 26 is a powered
actuator,
such as, but not limited to, an electrically or hydraulically driven
mechanism.
Referring again to Figure 7, the magnetic heater 2 further comprises a
controller
38. The controller 38 is in conununication with the spacing actuator 26, so as
to control
the conductor/magnet spacing X1. The controller 38 also is in communication
with the
shaft 18, so as to control the speed of motion of the magnet assembly 20, and
therefore,
the magnets 12, which derive their motion from the shaft 18, wherein the
output of the
motive device driving the shaft 18 is variable and controllable.
The fluid driver 34 is engaged with the magnet assembly 20 so that the speed
of
operation of the fluid driver 34, and consequently the rate of fluid flow
along the fluid
path 16, also is determined by the speed of motion of the magnet assembly 20.
The controller 38 in Figure 7 thus controls the rate of heat generation by
controlling the conductor/magnet spacing X1, and also controls the rate of
fluid flow by
controlling the rate at which the fluid driver 34 operates. By controlling
these two
parameters independently, the temperature of the fluid also can be controlled
as described
previously.
A variety of devices are suitable for use as a controller 38, including, but
not
limited to, integrated circuits. Controllers are known in the art, and are not
described
further herein.
Although the embodiment in Figure 7 shows the controller 38 in communication
with various sensors, it is emphasized that this is exemplary only. In other
embodiments,
18
CA 02532507 2006-01-09
the controller 38 controls the operation of the magnetic heater 2 without
sensors or data
therefrom. In embodiments in accordance with the present invention, the
controller 38
comprises stored data and/or a pre-calculated algorithm, based on, among other
things,
the design of the magnetic heater 2 and the performance of similar magnetic
heaters 2.
The controller 38 controls the magnetic heater 2 to produce the desired levels
of heat
generation, fluid temperature, and/or rate of fluid flow, without the need for
active
sensors to monitor the parameters of the magnetic heater 2 itself.
The embodiment in Figure 7 includes a fluid temperature sensor 40, for sensing
the temperature of fluid moving along the fluid path 16. It also includes a
fluid flow rate
sensor 42, for sensing the rate of fluid flow through the fluid path 16. It
further includes a
drive sensor 44, for sensing the rate at which the magnet assembly 20 is
driven by the
shaft 18. The controller 38 is in communication with each of the sensors 40,
42, and 44.
Based on data from the sensors 40, 42, and 44, the controller 38 adjusts the
speed
of the magnet assembly 20, the speed of the fluid driver 34, and/or the
conductor/magnet
spacing X1, so as to control heat generation, fluid temperature, and/or fluid
flow.
It is emphasized that the arrangement of the sensors 40, 42, and 44 as shown
is
exemplary only. It is not necessary for a particular embodiment to include
sensors at all,
or to include each of the sensors 40, 42, and 44 shown in Figure 7. In other
embodiments,
other sensors are included in the magnetic heater 2 in addition to or in place
of those
shown.
In one embodiment, the magnetic heater 2 comprises an additional sensor
adapted
to sense the conductor/magnet spacing X1 between the magnets 12 and the
conductive
member 14.
A variety of sensors are suitable for use in a magnetic heater 2 according to
embodiments of the present invention, depending upon the particulars of the
specific
embodiment of the magnetic heater 2 and the type of information that is to be
sensed.
Sensors are known in the art, and are not described further herein.
In previously described embodiments, the magnets 12 are restricted from moving
relative to the frame 22. In other embodiments of the present invention, the
magnets 12
are adapted to move relative to the frame 22. The relative motion of the
magnets 12 with
respect to the frame 22 facilitates a mode of control over the magnetic field
strength at
19
CA 02532507 2006-01-09
the conductive member 14 and thus controls the heating of the conductive
member 14
and the heat output of the magnetic heater 2.
In some embodiments in accordance with the present invention, apparatus for
moving the magnets 12 are passively operated; while in other embodiments, they
are
actively operated. In embodiments wherein the movement is active, the relative
movement is provided, among other means, by an actuator, such as a motor or
linear
drive mechanism.
Figure 10A is a side view of a rotatable magnet assembly 120 comprising a
frame
22, at least one magnet 12, and at least one passive relative-positioning
actuator 70a
adapted to move one or more magnets 12 in an axial direction X and a radial
direction Y
relative to the frame 22, in accordance with an embodiment of the present
invention.
Such movement can be exploited to control the magnetic field strength at the
conductive
member 14 by controlling, among other things, the conductor/magnet spacing X
1.
The passive relative-positioning actuator 70a comprises a pivot mount 69, a
first
linkage arm 72, a second linkage ann 74, a linkage guide 76, and a bias member
78. The
pivot mount 69 is adapted to couple with one or more magnets 12. The first
linkage ann
72 comprises a first linkage-arm first-end 73 and a first linkage-arm second-
end 71. The
first linkage-arm first-end 73 is pivotally coupled to the frame 22 and the
first linkage-
arm second-end 71 is pivotally coupled to the pivot mount 69. The second
linkage arm 74
comprises a second linkage-arm first-end 77 and a second linkage-arm second-
end 75.
The second linkage-arm first-end 77 is pivotally coupled to the pivot mount 69
and the
second linkage-arm second-end 75 is coupled in sliding engagement with the
linkage
guide 76.
The bias member 78 comprises a bias member first-end 178 and a bias member
second-end 278. The bias member second-end 278 is coupled to the second
linkage-arm
second-end 75 and the bias member first-end 178 is coupled to the frame 22
preferentially positioned to apply bias when the bias member second-end 278 is
moved in
a radial direction Y away from the x-axis. When the frame 22 is at rest, the
pivot mount
69 is positioned off-set from the center of gravity of the frame 22 towards
the intended
movement so that the centrifugal acceleration can move the magnet 12 in the
intended
direction.
CA 02532507 2006-01-09
The linkage guide 76 is adapted to guide and restrict the second linkage-arm
second-end 75 to movement in a substantially radial Y direction. Embodiments
of the
linkage guide 76 include, but are not limited to, a through-slot, track,
flange, and a race.
Rotation of the frame 22 about the x-axis induces centrifugal acceleration on
the
pivot mount 69 so as to urge the magnet 12 in a combination of movement away
from the
x-axis in a radial direction Y as well as lateral to the x-axis in the radial
direction X. The
first and second linkage arms 72, 74 pivot about their respective linkage-arm
ends 71, 73,
75, 77 as the second linkage-arm second-end 75, guided by the linkage guide
76, is
caused to slide from a first position A towards a second position B. The bias
member 78
is adapted to biasly control the movement of the second linkage-arm second-end
75
within the linkage guide 76, so as to provide a restoring force towards A when
moved
from A towards B.
A predetermined amount of bias for a particular purpose is determined by the
biasing properties of the bias member 78, the speed of rotation of the frame
22, the
weight of the pivot mount 69, and the magnet 12, and the first and second
linkage arms
72, 74, among other things.
The pivot mount 69 is pivotally coupled to the first and second linkage-arms
72,
74 in such a way so as to retain the first magnet surface 13 of the magnet 12
in a
substantially constant orientation parallel with the conductive member first
side 15 as the
magnet 12 moves relative to the frame 22. This coupling is done in any number
of
known ways, such as, but not limited to, cams, gears, and preferential weight
balance.
Figure 11 is a side view of a rotatable magnet assembly 120 wherein the second
linkage arm 74 is pivotally coupled to the first linkage arm 72 between the
first linkage-
arm first-end 73 and the first linkage-arm second-end 71.
Movement of the magnet 12 in both the radial direction Y and the axial
direction
X is used advantageously in a number of regards. In one embodiment, the magnet
12 is
positioned to move towards the conductive member 14 as the frame 22 is rotated
at a
faster rate inducing higher heating of the conductive member 14. Movement of
the
magnet 12 towards the conductive member 14 increases the magnetic field
strength at the
conductive member 14, increasing the rate of heating of the conductive member
14. The
rate of inductive heating of the conductive member 14, in part, is a function
of the square
21
CA 02532507 2006-01-09
of the separation distance of the magnet 12 from the conductive member 14.
Further, as the frame 22 is rotated faster, the magnet 12 is moved at a faster
rate
relative to the conductive member 14, increasing the cyclical variation of the
magnetic
field on the conductive member 14 and inducing a greater heating of the
conductive
member 14. The rate of inductive heating of the conductive member 14 is a
linear
function of the speed of rotation of the frame 22 with respect to the
conductive member
14. The combination of the squared function of inductive heating with
decreasing
conductor/magnet spacing X1 and the linear function of inductive heating with
increasing
speed of rotation, produces a heating rate somewhat higher than one of either
a change of
the conductor/magnet spacing Xl or rotation speed by themselves.
It is appreciated that the opposite effect occurs as the rate of rotation of
the frame
22 is decreased, producing a decreased component of heating due to the
increased
conductor/magnet spacing X1 and a reduced component of heating from the
reduced rate
of cyclical variation of the magnetic field, to produce a lower overall
heating of the
conductive member 14.
Referring again to Figure 10A, in another embodiment, a conductive member 14'
is positioned on a side of the rotatable magnet assembly 120 away from the
magnet 12
such that the pivot mount 69, and thus the magnet 12, is positioned to move
away from
the conductive member 14' as the frame 22 is rotated at a faster rate.
Movement of the
magnet 12 away from the conductive member 14 decreases the magnetic field
strength at
the conductive member 14', in turn decreasing the rate of heating of the
conductive
member 14' attributed to magnetic field strength.
Further, with the increase in the speed of movement of the magnet 12 as the
frame
22 is rotated faster, the cyclical variation of the magnetic field on the
conductive member
14' is also accelerated causing a greater heating of the conductive member
14'. The
combination of the squared function of reduced inductive heating with
increasing
conductor/magnet spacing X1 and the linear function of inductive heating with
increased
speed of rotation, is predetermined to produce a desired heating effect. This
counter-
balanced effect can be used to provide a magnetic heater that produces an
increase, a
constant, or a decreased amount of heat with increased rotation speed. In one
embodiment in accordance with the present invention, the rate of heat increase
due to a
22
CA 02532507 2006-01-09
higher rotation speed is substantially counter-balanced with the decrease in
the rare of
heat decrease as the conductor/magnet spacing X1 is increased, to produce a
constant
heating rate for a given range of rotation speed of the frame 22.
It is appreciated that the oppose effect occurs when the rate of rotation of
the
frame 22 is decreased, producing an increased component of heating from the
reduced
conductor/magnet spacing X1 and a reduced component of heating from the
reduced rate
of cyclical variation of the magnetic field, counter balanced to produce a
constant heating
of the conductive member 14'.
In another embodiment, the pivot mount 69, and thus the magnet 12, is
positioned
to move away from the conductive member 14 as the frame 22 is rotated at a
faster rate in
a predetermined way, inducing a decrease in the heating of the conductive
member 14.
Movement of the magnet 12 away from the conductive member decreases the
magnetic
field strength at the conductive member 14, decreasing the rate of heating of
the
conductive member 14 due to magnetic field strength. The rate of inductive
heating of the
conductive member 14 is a function of the square of the separation distance of
the magnet
from the conductive member 14.
Further, since the magnet 12 is being moved at a faster rate as the frame 22
is
rotated faster, the cyclical variation of the magnetic field on the conductive
member 14 is
also accelerated, causing a greater heating of the conductive member 14. The
rate of
inductive heating of the conductive member 14 is a linear function of the
speed of
rotation of the frame 22 with respect to the conductive member 14. The
combination of
the squared function of reduced inductive heating with increasing
conductor/magnet
spacing X1 and the linear function of inductive heating with increased speed
of rotation,
can be predetermined such that overall heat output provided by a magnetic
heater is
increased, remains constant, or is decreased with a faster rate of rotation of
the frame 22.
It is appreciated that the oppose effect occurs when the rate of rotation of
the
frame 22 is decreased, producing an increased component of heating from the
reduced
conductor/magnet spacing X1 and a reduced component of heating from the
reduced rate
of cyclical variation of the magnetic field, to produce an increase in heat
output.
Figure 12 is a side view of a rotatable magnet assembly 120 comprising a frame
22, at least one magnet 12, and at least one passive relative-positioning
actuator 70c
23
CA 02532507 2006-01-09
adapted to move one or more magnets 12 in an axial direction X and a radial
direction Y
relative to the frame 22, in accordance with an embodiment of the present
invention x-
axis in a radial direction Y as well as lateral to the x-axis in the radial
direction X. The
pivot mount 69, and thus the magnet 12, is positioned adjacent the conductive
member 14
such that the magnet 12 moves away from the conductive member 14 as the frame
22 is
rotated at a faster rate in a predetermined way, inducing a decrease in the
heating of the
conductive member 14. Such movement can be exploited to control the magnetic
field
strength at the conductive member 14 by controlling, among other things, the
conductor/magnet spacing X1.
The passive relative-positioning actuator 70c comprises a pivot mount 69, a
first
linkage arm 72, a second linkage arm 74, a linkage guide 76, and a bias member
78. The
pivot mount 69 is adapted to couple with one or more magnets 12. The first
linkage arm
72 comprises a first linkage-arm first-end 73 and a first linkage-arm second-
end 71. The
first linkage-arm first-end 73 is pivotally coupled to and coupled in sliding
engagement
with the linkage guide 76, and the first linkage-arm second-end 71 is
pivotally coupled to
the pivot mount 69. The second linkage arm 74 comprises a second linkage-arm
first-end
77 and a second linkage-arm second-end 75. The second linkage-arm first-end 77
is
pivotally coupled to the pivot mount 69 and the second linkage-arm second-end
75 is
pivotally coupled to the frame 22.
The bias member 78 comprises a bias member first-end 178 and a bias member
second-end 278. The bias member second-end 278 is coupled to the first linkage-
arm
first-end 73 and the bias member first-end 178 is coupled to the frame 22
preferentially
positioned to apply bias to the first linkage-arm first-end 73 when the bias
member
second-end 278 is moved in a radial direction Y away from the x-axis. When the
frame
22 is at rest, the pivot mount 69 is positioned off-set from the center of
gravity of the
frame 22 towards adjacent the conductive member 14 so that the centrifugal
acceleration
can move the magnet 12 in the intended direction.
The linkage guide 76 is adapted to guide and restrict the first linkage-arm
first-
end 73 to movement in a substantially radial direction Y. Embodiments of the
linkage
guide 76 include, but are not limited to, a through-slot, track, flange, and a
race.
In another embodiment, the second linkage arm 74 is pivotally coupled to the
first
24
CA 02532507 2006-01-09
linkage arm 72 substantially as shown in Figure 11.
Rotation of the frame 22 about the x-axis induces centrifugal acceleration on
the
pivot mount 69 so as to urge the magnet 12 in a combination of movement away
from the
x-axis in a radial direction Y as well as lateral to the x-axis in an axial
direction X. The
first and second linkage arms 72, 74 pivot about their respective linkage arm
ends 71, 73,
75, 77 as the first linkage-arm first-end 73, guided by the linkage guide 76,
is caused to
slide from a first position A towards a second position B. The bias member 78
is adapted
to biasly control the movement of the first linkage-arm first-end 73 within
the linkage
guide 76, so as to provide a restoring force towards A when moved from A
towards B.
A predetermined amount of bias for a particular purpose is determined by the
biasing properties of the bias member 78, the speed of rotation of the frame
22, and the
weight of the pivot mount 69, magnet 12, and first and second linkage arms 72,
74,
among other things.
The pivot mount 69 is pivotally coupled to the first and second linkage arms
72,
74 in such a way so as to retain the first magnet surface 13 of the magnet 12
in a
substantially constant orientation parallel with the conductive member first
side 15 as the
magnet 12 moves relative to the frame 22. This is done in any number of known
ways,
such as, but not limited to, cams, gears, and preferential weight balance.
Figure 13 is a side view of a rotatable magnet assembly 322 comprising a frame
22 and at least one passive relative positioning actuator 20d, in which the
magnets 12 are
adapted to move relative to the frame 22, in substantially the same way as for
the
embodiments of Figure 10A, in accordance with an embodiment of the present
invention.
Such movement can be exploited to control the magnetic field strength at the
conductive
member 14 as previously discussed.
The frame passive relative positioning actuator 20d further comprises a pivot
arm
82, a pivot mount 69 adapted to couple with a magnet 12, and a bias member 78.
The
pivot arm 82 comprises a pivot arm first-end 83 and a pivot arm second-end 81.
The
pivot arm first-end 83 is pivotally coupled to the frame 22 and the pivot arm
second-end
81 is pivotally coupled to the pivot mount 69. The bias member 78 comprises a
bias
meinber first-end 178 and a bias member second-end 278. The bias member first-
end
178 is coupled to the frame 22 and the bias member second-end 278 is coupled
to the
CA 02532507 2006-01-09
pivot arm second-end 81. The pivot mount 69 is positioned, when the frame 22
is at rest,
at an off-set from the center of gravity of the frame 22 towards the intended
movement so
that the centrifugal acceleration can move the magnet 12 in the intended
direction.
Rotation of the frame 22 about the x-axis induces centrifugal acceleration on
the
pivot mount 69, and thus the magnet 12, so as to urge the magnet 12 in a
combination of
movement away from the x-axis in a substantially radial direction Y as well as
along the
x-axis in an axial direction X. The pivot arm 82 pivots about the frame 22 at
the pivot
arm first-end 83. The bias member 78 is adapted to biasly control the movement
of the
pivot arm second-end 81.
The amount of bias is determined by the biasing properties of the bias member
78,
the speed of rotation of the frame 22, and the weight of the pivot mount 69,
the magnet
12 and the pivot arm 82, among other things.
The pivot mount 69 is pivotally coupled to the pivot arm second-end 81 so as
to
retain the magnet 12 is a substantially constant orientation parallel with the
conductive
member 14. This can be done in any number of known ways, such as, but not
limited to,
cams, gears, and preferential weight balance.
In operation, as the frame 22 is rotated at a faster rate, centrifugal
acceleration
moves, or tends to move, the magnet 12 in a combination of radial direction Y
and an
axial direction X. The bias member 78 controls the extent of movement of the
magnet 12
by controlling the movement of the pivot arm 82, to between positions A and B.
As the
frame 22 is rotated at a faster rate, the bias member 78 is further overcome
so as to allow
movement of the magnet 12 towards position B. As the rate of rotation of frame
22 is
reduced, the bias member 78 urges the pivot arm second-end 81 towards position
A.
Movement of the magnet 12 in both the radial direction Y and the axial
direction
X can be used advantageously in a number of regards, as previously described
above for
the embodiment of Figure 10A.
Referring again to Figures 10A, 11, 12 and 13, other embodiments replace the
bias member 78 with a biased pivot pin 79. Such biased pivot pins 79,
otherwise known
as self-closing hinges and spring-loaded pivot pins, are generally known in
the art. The
biased pivot pin 79 is utilized in substantially the same way as the bias
member 78
previously described. The biased pivot pin 79 is adapted to provide a
restoring force so
26
CA 02532507 2006-01-09
as to move the magnet 12 toward position A. The biased pivot pin 79 can be
made so as
to be less intrusive to the flow path.
Figures 14A and 14B are front and side views of a bimetallic spring frame 422
comprising one or more slots 402, each defining an axial-facing tang 404. The
tang 404
is adapted to couple with at least one magnet 12 or at least one conductive
member 27.
The tang 404 comprises a first material 408 having a first coefficient of
thermal
expansion and a second material 409 having a second coefficient of thermal
expansion to
form a bimetallic spring 400.
As the temperature of the bimetallic spring 400 rises, the bimetallic spring
causes
the tang 404 to deflect away. This movement can be used to move the magnet 12,
or the
conductor 27, away from the conductive member 14, or the magnet 12, thereby
reducing
the heating of the conductive member 27. In an embodiment, this provides a
predetermined self-managing function such that the heat output remains
substantially
constant for a range of rotation speeds. In another embodiment, this provides
a
predetermined self-limiting function, whereas a maximum heat output is
obtained above a
predetermined rotation speed.
Figures 15A and 15B are side and front views of a rotatable magnet assembly
520
comprising a frame 22, at least one passive relative-positioning actuator 70f,
and a
magnet 12, in accordance with an embodiment of the present invention. The
passive
relative-positioning actuator 70f is adapted to move the magnet 12 in a radial
direction
relative to the frame 22. Radial movement of the magnet 12 can be exploited to
control
the magnetic field strength on the conductive member 14. The passive relative-
positioning actuator 70f comprises a mount 169, a guide pin 85, and a bias
member 78.
The frame 22 further comprises a pin guide 86 adapted to slidingly receive the
guide pin
85. The pin guide 86 is adapted to couple with the guide pin 85 to allow
movement of the
guide pin 85 about the pin guide 86 in the radial direction Y. The guide pin
86 is coupled
to the mount 165 that is adapted to couple with the magnet 12. The bias member
78
comprises a bias member first-end 178 and a bias member second-end 278. The
bias
member first-end 178 is coupled to the frame 22 and the bias member second-end
278 is
coupled to the mount 169.
Rotation of the frame 22 about the x-axis induces centrifugal acceleration on
the
27
CA 02532507 2006-01-09
magnet 12 so as to urge the magnet 12, guided by the guide pin 85 within the
pin guide
86, away from the x-axis in a substantially radial direction Y. The guide pin
85, coupled
within the pin guide 86, is adapted to slide from a first position A towards a
second
position B. The bias member 78 is adapted to biasly control the movement of
the guide
pin 85 within the pin guide 86 and to provide a restoring force to bias the
magnet 12 back
to position A when the frame 22 is not rotated or at a predetermined rate of
rotation.
The amount of bias is determined by the biasing properties of the bias member
78,
the speed of rotation of the frame 22, and the weight of the mount 169 and the
magnet 12,
among other things.
The magnet 12 is coupled to the mount 169 that is adapted to retain the magnet
12 in a constant orientation parallel with the conductive member 14.
In operation, as the frame 22 is rotated at a faster rate, centrifugal
acceleration
will move, or tend to move, the magnet 12 in a radial Y direction. In other
embodiments,
other passive relative-positioning actuators that provide radial positioning
are anticipated,
including a trolley and track assembly, among others.
Relative movement between the magnets 12 and the conductive member 14
induces the heating of the conductive member 14. This is regardless of whether
only the
magnet 12 is moving or only the conductive member 14 is moving, or both are
moving
relative to each other. The embodiments of Figures 10A, 11, 12, 13, 14, and
15,
therefore, can be used to move the conductive member 14 rather than the magnet
12, to
produce substantially the same result. In embodiments in accordance with the
present
invention, the conductive member, such as the conductive member 27 shown in
Figure 4,
is coupled to the pivot mount 69, shown in Figures 10A, 11, 12, 13, 14, and 15
and
positioned and rotated adjacent stationary magnets 14.
Figure l OB is a side view of a conductive member assembly 140 comprising a
conductive member frame 122, at least one conductive member 27, and at least
one
passive relative-positioning actuator 70a adapted to move one or more
conductive
members 27 in an axial direction X and a radial direction Y relative to the
conductive
member frame 122, in accordance with an embodiment of the present invention.
Figure 16A is a front view of the conductive member 14 comprising a disc, in
accordance with an embodiment of the present invention. The magnet 12 is shown
to be
28
CA 02532507 2006-01-09
moving relative to the conductive member 14 in a radial direction Y between
position A
and position B. As the magnet assembly (not shown) rotates at an increasing
speed of
rotation, the magnet 12 moves radially from position A to position B.
Figure 16B shows a temperature curve 160 illustrating the trend in the
temperature generated in the conductive member 14 with the change in axial
position of
the magnet 12 that is directly related to the speed of rotation of the frame.
The
temperature curve 160 shows that heating increases as the rotation speed of
the frame is
increased. The heating decreases drastically as the magnet 12 traverses the
peripheral
edge 25 of the conductive member 14.
Figure 17A is a front view of the conductive member 114 comprising a star
shape,
in accordance with an embodiment of the present invention. The magnet 12 is
shown to
be moving relative to the conductive member 14 in a radial direction Y between
position
A and position B. As the magnet assembly (not shown) rotates at an increasing
speed of
rotation, the magnet 12 moves radially from position A to position B. The
conductive
member 114 comprises a substantially disc-shaped central portion 172 and a
plurality of
arms 171 extending radially from the central portion 172. The arms 171 are of
a
predetermined shape for a particular purpose. The arms terminate at a
peripheral edge
173 that define a circular arc 125 when rotating. The arms 171 present a
reduced cross-
sectional area that is exposed to the magnet 12 when adjacent the magnet 12 as
compared
with the disc-shaped conductive member 14 of Figure 16A.
Figure 17B shows a temperature curve 170 illustrating the trend in the
temperature generated in the conductive member 114 with the change in axial
position of
the magnet 12. As the magnet 12 moves in a radial direction Y, the magnet 12
moves
from adjacent the central portion 172 to adjacent to the arms 171 exposing a
reduced
surface area of the conductive member 114 to the varying magnetic field. With
less
surface area of the conductive member 114 available to heat the heat transfer
fluid, the
result is reduced heat output from the magnetic heater. In one embodiment, the
arms
171 are tapered a predetermined amount so as to produce a constant heat output
of the
heater regardless of the radial position of the magnet 12, up to approaching
the peripheral
edge 173 of the arms 171. In another embodiment, the arms 171 are tapered so
as to
provide more surface area such that the heat output is increased or so as to
provide less
29
CA 02532507 2006-01-09
surface area such that the heat output is decreased. The heating decreases
drastically as
the magnet 12 traverses the peripheral edge 125 of the conductive member 114.
Figure 18A is a front view of the conductive member 214 comprising multiple
rings, in accordance with an embodiment of the present invention. The magnet
12 is
shown to be moving relative to the conductive member 14 in a radial direction
Y between
position A and position B. As the magnet assembly (not shown) rotates at an
increasing
speed of rotation, the magnet 12 moves radially from position A to position B.
The
conductive member 214 comprises a plurality of individual rings: an inner ring
181, an
intermediate ring 182, and an outer ring 183.
Figure 18B shows three temperature curves 184, 185, and 186 illustrating the
trend in the temperature generated in the conductive member 14 with the change
in axial
position of the magnet 12 that is directly related to the speed of rotation of
the frame for
three embodiments. The temperature curve 184 shows that heating increases as
the
rotation speed of the frame is increased and the magnet 12 moves in a radial
direction.
The magnet 12 moves from adjacent the inner ring 181 to adjacent the
intermediate ring
182, and then to adjacent the outer ring 183. In one embodiment, the inner
ring 181,
intermediate ring 182, and outer ring 183 are configured in a predetermined
way so as to
produce an increase in heating on the conductive member, as shown in the
temperature
graph of Figure 18B, curve 184. The ring geometry, composition, and
dimensions,
among other things, are predetermined so that the combination of increased
rotation
speed producing an increase in magnetic variance and the increased surface
area produces
a net increase in heating of the heat transfer fluid. The heating decreases
drastically as the
magnet 12 traverses the peripheral edge 225 of the conductive member 214.
In another embodiment, as illustrated by curve 185, the inner ring 181,
intermediate ring 182, and outer ring 183 are predetermined so as to produce a
substantially constant heating on the conductive member regardless of the
radial position
of the magnet 12, up to approaching the peripheral edge 225 of the outer ring
183. In one
embodiment, the surface area is configured so that the combination of
increased rotation
speed producing an increase in magnetic variance is counterbalanced by a
reduced
surface area to produce a net constant heating of the heat transfer fluid.
In another embodiment, as illustrated by curve 186, the inner ring 181,
CA 02532507 2006-01-09
intermediate ring 182, and outer ring 183 are predetermined so as to produce a
decrease
in heating. In one embodiment, the ring surface area is configured so that the
combination of increased rotation speed producing an increase in magnetic
variance and a
decrease in surface area produces a net decrease in heating of the heat
transfer fluid.
Figure 19 is a side view of a magnetic heater 4 in accordance with an
embodiment
of the present invention. A conductive member 14 comprises a conductive member
first
side 15a and a conductive member second side 15b. A first magnet assembly 20a
comprising a first frame 22a and a plurality of first magnets 12a thereon is
disposed a
first spacing X3 away from the conductive member first side 15a. Similarly, a
second
magnet assembly 20b comprising a second frame 22b and a plurality of second
magnets
12b thereon is disposed a second spacing X4 away from the conductive member
second
side 15b of the conductive member 14.
The first and second magnet assemblies 20a, 20b are disposed adjacent the
conductive member first and second sides 15a, 15b, respectively, such that the
magnets
12a and 12b, respectively, are aligned with one another to form opposing pairs
on each
side 15a, 15bof the conductive member 14. In an embodiment wherein the first
and
second magnet assemblies 20a, 20b are movable, they are movable together so as
to
maintain in opposing magnets pairs.
Figure 20 is a partial view of the embodiment of Figure 19, wherein different
polarities of opposing magnets 12a, 12b face the conductive member 14, to
present a
predetermined gradient in the magnetic field. In another embodiment (not
shown), the
same polarity of opposing magnets 12a, 12b face the conductive member 14, to
present a
predetermined gradient in the magnetic field that is produced.
Figure 21 is an embodiment of a multi-stage magnetic heater 6, in accordance
with the present invention. As with the embodiment shown in Figure 1, the
embodiment
of Figure 19 may be conveniently expanded by the use of additional conductive
members
14 and magnet assemblies 20. The embodiment of Figure 21 comprises an
arrangement
with three conductive members 14a-c and four magnet assemblies 20a-d. It is
noted that
the number of conductive members 14 and magnets 12 is exemplary only, and that
other
numbers and arrangements may be equally suitable.
The multi-stage magnetic heater 6 further comprises support bracing 90
coupling
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CA 02532507 2006-01-09
the plurality of magnet assemblies 20a-d in relative axial alignment. It is
appreciated that
the operation of the magnetic heater 6 is effected whether the magnet
assemblies 14a-d or
the conductive members 14a-c are driven to rotation by the shaft 18.
Figures 22 and 23 are assembled and exploded views of a magnetic heater
apparatus 8 in accordance with an embodiment of the present invention. The
magnetic
heater apparatus 8 comprises a rear housing 94, a first end plate 91, a heater
housing 92, a
magnetic heater 6, a second end plate 93, a blower housing 96, and an air
intake screen
97.
The magnetic heater 6, in accordance with the embodiment of Figure 19,
comprises a shaft 18, a first magnet assembly 20a, a conductive member 14, a
second
magnet assembly 20b and a fluid driver 34. The first and second magnet
assemblies 20a,
20b comprise a plurality of magnets 12. The conductive member 14 is disposed
between
and coaxial with the first and second magnet assemblies 20a, 20b. The
conductive
member 14 is coupled with the shaft 18 and adapted to rotate with respect to
the first and
second magnet assemblies 20a, 20b. The shaft 18 is adapted to couple with an
energy
source 103.
The rear housing 94 is coupled adjacent the first end plate 91, both
comprising
apertures to allow the shaft 18 to pass therethrough. The first end plate is
coupled
adjacent the heater housing 92 defining a volume adapted to contain the first
and second
magnet assemblies 20a, 20b and conductive member 14. The second end plate 93
is
coupled adjacent the heater housing 92 defining a side of the volume. The
heater housing
92 comprises a fluid outlet 102. The second end plate 93 comprises a second
end plate
aperture 95 defining a portion of a fluid path. The fluid driver 34 is coupled
to the shaft
18 and located adjacent the second end panel 93 on the opposite side from the
second
magnet assembly 20b. The blower housing 96 is coupled adjacent the second end
panel
93 enclosing the fluid driver 34 therebetween. The blower housing 96 defines a
fluid
inlet aperture 87 defining a portion of the fluid path. The air intake screen
97 is coupled
to the blower housing 96 covering the fluid inlet aperture 87.
A fluid path is defined by the fluid inlet aperture 87, the fluid driver 34,
the
second end plate aperture 95, the heater housing 92 and the fluid outlet 102.
Fluid is
drawn into the fluid inlet aperture 87 by the rotation of the fluid driver 34.
The fluid
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CA 02532507 2006-01-09
driver 34 directs the fluid through the second end plate aperture 95 and
circulates the
fluid past the conductive member 14 in the heater housing 92. The heater
housing 92
directs the fluid to the fluid outlet 102.
The magnetic heater apparatus 8 further comprises a spacing adjustment
assembly
103 comprising a knob 99, a threaded spacer 105 having a first spacer end 108
and a
second spacer end 109, a first retention coupler 107 and a second retention
coupler 106.
The first retention coupler 107 is positioned adjacent the first magnet
assembly 20a and
the second retention coupler 109 is positioned adjacent the second magnet
assembly 20b.
The threaded spacer 105 is disposed between the first and second magnet
assemblies 20a,
20b, the first spacer end 108 coupled with the first retention coupler 107.
The second
spacer end 109 is passed through the second retention coupler 106 and coupled
to the
knob 99. Turning the knob 99 in a first direction reduces the spacing between
the first
and second magnet assemblies 20a, 20b. Turning the knob 99 in the opposite
direction
increases the spacing between the first and second magnet assemblies 20a, 20b.
Although specific embodiments have been illustrated and described herein for
purposes of description of the preferred embodiment, it will be appreciated by
those of
ordinary skill in the art that a wide variety of alternate and/or equivalent
implementations
calculated to achieve the same purposes may be substituted for the specific
embodiments
shown and described without departing from the scope of the present invention.
Those
with skill in the art will readily appreciate that the present invention may
be implemented
in a very wide variety of embodiments. This application is intended to cover
any
adaptations or variations of the embodiments discussed herein.
Persons skilled in the art will recognize that many modifications and
variations
are possible in the details, materials, and arrangements of the parts and
actions which
have been described and illustrated in order to explain the nature of this
invention and
that such modifications and variations do not depart from the spirit and scope
of the
teachings and appended claims contained.
33
