U.S. patent application number 14/553577 was filed with the patent office on 2015-05-28 for high volume low speed fan using direct drive transverse flux motor.
The applicant listed for this patent is MacroAir Technologies, Inc.. Invention is credited to Michael W. Danielsson.
Application Number | 20150147188 14/553577 |
Document ID | / |
Family ID | 53182821 |
Filed Date | 2015-05-28 |
United States Patent
Application |
20150147188 |
Kind Code |
A1 |
Danielsson; Michael W. |
May 28, 2015 |
High Volume Low Speed Fan Using Direct Drive Transverse Flux
Motor
Abstract
Disclosed is a high volume low speed (HVLS) fan that is designed
to circulate air in large buildings for cooling, heating, and
ventilation. A fan with a diameter between 8 to 24 feet consisting
of a plurality of blades, with each in the shape of a tapered
airfoil, is driven by a direct drive transverse flux electric motor
to produce a very large slowly moving column of air. The HVLS
system preferably includes motion and angular shutdown, voltage
recognition, blade size recognition and data logging for recording
the last 100 or so hours of operation to facilitate warranty
applicability and assist in trouble shooting as well as software
updates and programming via Bluetooth and internet keypad.
Inventors: |
Danielsson; Michael W.;
(Riverside, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MacroAir Technologies, Inc. |
San Bernardino |
CA |
US |
|
|
Family ID: |
53182821 |
Appl. No.: |
14/553577 |
Filed: |
November 25, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61908542 |
Nov 25, 2013 |
|
|
|
Current U.S.
Class: |
417/14 ; 417/42;
417/44.1 |
Current CPC
Class: |
F04D 25/088 20130101;
F04D 27/004 20130101; F04D 25/0613 20130101; H02K 2201/12 20130101;
F24F 11/30 20180101; H02K 1/145 20130101; H02K 7/14 20130101; F24F
2110/20 20180101; F24F 7/007 20130101 |
Class at
Publication: |
417/14 ;
417/44.1; 417/42 |
International
Class: |
F04D 27/00 20060101
F04D027/00; F04D 25/08 20060101 F04D025/08; F24F 7/007 20060101
F24F007/007 |
Claims
1. A fan for use in a building comprising: a transverse flux motor
operably coupled to a plurality of struts; a plurality of fan
blades mounted to and extending outwardly from the plurality of
struts; a controller in operable communication with a user
interface and the transverse flux motor.
2. The fan of claim 1, wherein the controller is configured to
operate the transverse flux motor to provide cooling in the
building in response to human input to the user interface.
3. The fan of claim 1, wherein the controller is configured to
receive a humidity input from a humidity sensor.
4. The fan of claim 1, wherein the controller is configured to
receive a temperature input from a temperature sensor.
5. The fan of claim 1, wherein the controller is configured to
provide automatic resumption of blade rotation when a fault code is
corrected.
6. The fan of claim 1, wherein the controller is configured to
integrate with a building management system.
7. The fan of claim 1, wherein the controller is configured to
sense the rotational speed of the fan and confirm that the speed is
within the tolerance for the selected blade diameter profile.
8. A fan for use in a building comprising: a transverse flux motor
directly coupled to a plurality of struts; a plurality of fan
blades mounted to and extending outwardly from the plurality of
struts; and a controller in operable communication with a user
interface and the transverse flux motor, the controller configured
to (i) operate the transverse flux motor to provide air flow in the
building in response to human input through the user interface,
(ii) operate the transverse flux motor to provide a high volume of
low speed air in response to an input from a humidity sensor, (iii)
operate the transverse flux motor to provide a high volume of low
speed air in response to a temperature input from a temperature
sensor, (iv) provide automatic resumption of blade rotation when a
fault code is corrected, (v) receive input from a building
management system, and (vi) operate the transverse flux motor with
a wide range of voltage magnitude.
9. The fan of claim 8, wherein the user interface comprises a
software option for selecting the speed of rotation of the
transverse flux motor.
10. The fan of claim 8, further comprising a memory module in
communication with the controller, the memory module for storing
user preferred operating parameters.
11. The fan of claim 8, wherein the controller monitors rotational
speed, load and motion variations.
12. The fan of claim 8, wherein the controller recognizes blade
size.
13. The fan of claim 8, wherein controller software updates may be
uploaded through a Modbus device or Bluetooth.
14. The fan of claim 8, wherein troubleshooting of the controller
and transverse flux motor may be performed through a Modbus
device.
15. The fan of claim 8, wherein the building management system
further integrates the fan with lighting, heating and cooling
systems, doors and other features connected to the system.
16. The fan of claim 8, wherein an hour meter is in operable
communication with the controller for monitoring the duration of
operation of the transverse flux motor.
17. The fan of claim 8, wherein the wide range of voltage magnitude
is from 110 to 636 volts.
18. The fan of claim 17, wherein single phase or three phase
voltages are recognized by the controller.
19. The fan of claim 8, wherein the controller monitors hours of
operation for warranty purposes.
Description
RELATED APPLICATION
[0001] This application claims the benefit of priority to U.S.
Provisional Application No. 61/908,542 filed on Nov. 25, 2013.
TECHNICAL FIELD
[0002] The present disclosure relates to high volume low speed fans
utilizing a direct drive transverse flux motor and control system
configured in accordance with principles of the present
disclosure.
BACKGROUND
[0003] People who work in large structures such as warehouses and
manufacturing plants are routinely exposed to working conditions
that range from being uncomfortable to hazardous. On a hot day, the
inside air temperature can reach a point where a person is unable
to maintain a healthy body temperature. Moreover, many activities
that occur in these environments, such as welding or operating
internal combustion engines, create airborne contaminants that can
be deleterious to those exposed. The effects of airborne
contaminants are magnified to an even greater extent if the area is
not properly vented.
[0004] The problem of cooling large structures cannot always be
solved using conventional air-conditioning methods. In particular,
the large volume of air that is enclosed within a large structure
would require powerful air conditioning devices to be effective. If
such devices were used, the operating costs would be substantial.
The cost of operating large air conditioning devices would be even
greater if large doors where routinely left in an open state or if
ventilation of outside air was required.
[0005] In general, fans are commonly used to provide some degree of
cooling when air conditioning is not feasible. A typical fan
consists of a plurality of pitched blades radially positioned on a
rotatable hub. The tip-to-tip diameter of such fans typically range
from 3 feet up to 5 feet.
[0006] When a typical fan rotates under the influence of a motor at
higher rotational speeds, a pressure differential is created
between the air near the fan blades and the surrounding air,
causing a generally conical flow of air that is directed along the
fan's axis of rotation. The conical shape combined with drag forces
acting at the boundary of the moving mass of air cause the airflow
pattern to flare out in a diffusive manner at downstream locations.
As a consequence, the ability of these types of fans to provide
effective and efficient cooling can be limited for individuals
located at a distance from the fan.
[0007] In particular, the effectiveness of a fan is based on the
principle of evaporation. When the temperature of a human body
increases beyond a threshold level, the body responds by
perspiring. Through the process of evaporation, the more energetic
molecules comprising the perspiration are released into the
surrounding air, thus resulting in an overall decrease in the
thermal energy of the exterior of the individual's body. The
decrease in thermal energy due to evaporation serves to offset
positive sources of thermal energy in the individual's body
including metabolic activity and heat conduction with surrounding
high temperature air.
[0008] The rate of evaporative heat loss is highly dependent on the
relative humidity of the surrounding air. If the surrounding air is
motionless, then a layer of saturated air usually forms near the
surface of the individual's skin which dramatically decreases the
rate of evaporative heat loss as it prevents the evaporation from
the individual's body. At this point, perspiration builds up
causing the body to break out into a sweat. The lack of an
effective heat loss mechanism results in the body temperature
increasing beyond a desired level.
[0009] The airflow created by a fan helps to break up the saturated
air near the surface of a person's skin and replace it with
unsaturated air. This effectively allows the process of evaporation
to continue for extended periods of time. The desired result is
that the body temperature remains at a comfortable level. In large
buildings, the conventional strategy for cooling individuals has
been to employ many commonly available small diameter indoor fans.
Small diameter fans have been favored over large diameter fans
primarily because of physical constraints. In particular, large
diameter fans require specially constructed high-strength
light-weight blades that can withstand large stresses caused by
significant gravitational moments that increase with an increasing
blade length to width aspect ratio. In addition, the fact that the
rotational inertia of the fan increases with the square of the
diameter requires the use of high torque producing gear reduction
mechanisms. Moreover, drive-train components are highly susceptible
to mechanical failure due to the very large torques produced by
conventional electric motors during their startup phase.
[0010] A drawback of using a conventional small diameter fan to
create a continuous flow of air is that the resulting airflow
dramatically decreases at downstream locations. This is due to the
conical nature of the airflow combined with the relatively small
mass of air that is contained in the airflow in comparison to
resistive drag forces acting at the edge of the cone. To achieve a
sufficient airflow in a large non-insulated building, a very large
number of small diameter fans would be required. However, the large
amount of electrical power required by the simultaneous use of
these devices in great numbers negates their advantage as an
inexpensive cooling system. Moreover, the use of many fans in an
enclosed space can also result in increased air turbulence that can
actually decrease the air flow in the building thereby decreasing
the cooling effect of the fan.
[0011] To achieve a sufficient airflow in large buildings without
relying on an impractically large number of small diameter fans, a
small number of small diameter fans are typically operated at very
high speeds. However, although these types of fans are capable of
displacing a large amount of air in a relatively small amount of
time, they do so in an undesirable manner. In particular, a small
high speed fan operates by moving a relatively small amount of air
at a relatively high speed. Consequently, the speed of the airflow
adjacent the fan and the level of noise produced are both very
high. Furthermore, lighter weight objects, such as papers, may get
displaced by the high speed air flow, thus causing a major
disruption to the work environment.
[0012] Another problem with high speed fans is that they are
inefficient at entraining a large enclosed volume of air in a
steady continuous airflow pattern. In particular, assuming a best
case scenario of laminar airflow, the power consumption of a fan is
proportional to the cube of the airspeed produced by the fan.
Consequently, an electrically driven high speed fan having a
correspondingly high speed airflow consumes electrical power at a
relatively large rate. Furthermore, the effects of turbulence,
which become more pronounced as the speed of the airflow increases,
cause the translational kinetic energy associated with the airflow
of a high speed fan to be dissipated within a relatively small
volume of air. Consequently, even though a relatively large amount
of electrical power is consumed by the high speed fan, negligible
airflows are produced at locations that are distant from the
fan.
[0013] To overcome insufficient airflow problems, larger numbers of
high speed fans are sometimes used. However, this solution
increases the ambient noise and operating costs even further. In
addition, regions of fast moving air are expanded, thus increasing
the risk of injury to exposed individuals. In particular, if the
air is moving fast enough, foreign objects can become airborne,
thus causing a hazardous situation. Papers and other light objects
can also be greatly affected. Moreover, if the air temperature is
above the skin temperature of an individual, then air moving faster
than what is needed to break up the boundary layer actually reduces
the cooling effect due to the increased rate of heat flow from the
higher temperature air to the lower temperature skin of the
individual.
[0014] In addition to cooling, fans are also relied upon in
ventilation systems that serve to remove airborne contaminants such
as exhaust or smoke. Typical ventilation systems consist of a set
of high speed fans located at the perimeter of the structure.
However, the previously mentioned problems of high speed fans apply
to high speed ventilation fans. The most serious problem is that
some areas inside the structure are not properly ventilated.
[0015] To improve ventilation, high speed indoor fans are sometimes
used to distribute contaminants throughout the entire volume of a
structure. However, the same limitations of high speed indoor fan
systems described earlier apply to the problem of ventilation. In
particular, high speed indoor fans are loud, inefficient, provide
an insufficient airflow to some regions, and provide an undesirably
large airflow to others.
[0016] From the foregoing reasons, it will be appreciated that
there is a need for a cost efficient cooling device that can be
effectively operated in large buildings. Furthermore, there is a
need for such a device that is very efficient and does not disrupt
the work environment with excessive noise or high speed airflows.
Furthermore, there is a need for such a device that will dilute
concentrated pockets of contaminated air contained within the
structure more uniformly, thus providing optimal ventilation to the
structure when used in conjunction with a conventional ventilation
system.
[0017] For the foregoing reasons, there is a need for a high volume
low speed (HVLS) fan with an efficient electric motor that is
capable of operating at various rotational speeds and/or loads, and
preferably low rotational speeds. The motor must be capable of
being operated within a narrow RPM range and/or load range at a
suitable efficiency.
[0018] For the foregoing reasons there is a need for an HVLS fan
that avoids being gear driven due to the maintenance and in
particular in relation to the lubrication requirements. Gear box
seals can develop leaks and should the oil seep out, the gear
mechanism can lock up due to lack of lubrication because of the
gear metal to metal contact. Gear boxes also generate heat which
can be counterproductive in a setting where the objective is to
provide cooling.
[0019] For the foregoing reasons, there is a need for an HVLS fan
motor capable of being operated efficiently at low rotational
speeds with sufficient torque and a minimal need for periodic
maintenance and repairs. HVLS gearboxes are traditionally coupled
to an electric motor to achieve a desired output RPM or other
output condition. However, gearboxes are often costly, bulky,
heavy, and/or impose additional energy losses, for example
frictional losses. Such mechanical components can reduce the
overall efficiency of the combined system. For example, an electric
motor operating at about 85% efficiency coupled to a gearbox
operating at about 65% efficiency results in a motor/gearbox system
having an overall efficiency of about 55%. Moreover, a gearbox may
be larger and/or weigh more or cost more than the conventional
electric motor itself. Gearboxes also reduce the overall
reliability of the system.
[0020] For the foregoing reasons, there is a need for an HVLS fan
with an electric motor that does not contain large volumes of
copper wire or other coil material. Due to the length of the coil
windings, resistive effects in the coil lead to coil losses. Such
losses convert a portion of electrical energy into heat, reducing
efficiency and potentially leading to thermal damage to and/or
functional destruction of the motor and raising the ambient
temperature within the structure being cooled.
[0021] For the foregoing reasons, there is a need for an HVLS fan
to include a sensor that comprises an accelerometer, wherein the
accelerometer is configured to communicate a signal to the control
system in response to detecting an impact against the fan system or
an imbalance of the fan system.
[0022] For the foregoing reasons, there is a need for a method for
controlling the operation of the HVLS from a remote location using
a communication modality such as infrared (IR), BlueTooth (BT) or
Wi-Fi. A communication link is established with the HVLS and
instructions may then be transmitted to the control system via the
communication modality.
SUMMARY
[0023] This disclosure relates to a HVLS fan that is powered by a
transverse flux motor. An exemplary transverse flux motor may
comprise a rotor, a stator, and a coil. Moreover, a transverse flux
machine may be configured with any suitable components, structures,
and/or elements in order to provide desired electrical, magnetic,
and/or physical properties.
[0024] In an exemplary embodiment, an HVLS fan is driven by a
transverse flux motor wherein the HVLS fan does not utilize a
gearbox, and/or similar mechanical component(s). In this exemplary
embodiment, the HVLS fan is significantly lighter than a similarly
sized HVLS fan driven by a traditional electric drive motor
utilizing a gear box. The reduced weight will facilitate an
increase in motor efficiency, reduced noise and few components
requiring maintenance.
[0025] In an exemplary embodiment, an HVLS fan driven by a
transverse flux motor will have a broad RPM range of suitable
efficiency and/or suitable output torque and may desirably be
utilized in a variety of HVLS fan applications where a direct-drive
configuration is advantageous. For example, a transverse flux motor
having an efficiency greater than 80% over an RPM range from only a
few RPMs to about 300 RPMs is highly desirable in nearly all HVLS
settings.
[0026] Another drawback to existing HVLS fans is the level of noise
generated by existing drive systems. Whether driven by a
traditional magnetic motor or by a transverse flux motor existing
drive systems currently include a gear box in order to achieve
sufficient torque to start rotation of the fan blades and to drive
them at the higher rpm range allowing the fan to overcome
resistance generated by the blades moving through the air.
[0027] In another exemplary embodiment, an HVLS fan will utilize an
accelerometer. In the event of either an impact or a significant
imbalance condition, the accelerometer may detect a lateral
acceleration resulting from the impact or imbalance, and may send a
corresponding signal to an onboard control system. The
accelerometer sensor and control circuitry is preferably integrated
into the control system.
[0028] In another exemplary embodiment, an HVLS fan will
incorporate a communication modality such as infrared (IR),
BlueTooth (BT) or Wi-Fi. A communication link is established with
the HVLS and instructions may then be transmitted to the control
system via the communication modality.
[0029] Various objects, features, aspects and advantages of the
inventive subject matter will become more apparent from the
following detailed description of preferred embodiments, along with
the accompanying drawings in which like numerals represent like
components. The contents of this summary section are provided only
as a simplified introduction to the disclosure, and are not
intended to be used to limit the scope of the appended claims.
[0030] The contents of this summary section are provided only as a
simplified introduction to the disclosure, and are not intended to
be used to limit the scope of the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 is a perspective view of an embodiment of a high
volume low speed (HVLS) fan system;
[0032] FIG. 2 is a cutaway view of an embodiment of a transverse
flux motor;
[0033] FIG. 3 is a perspective view of an embodiment of a HVLS fan
detailing the controller components; and
[0034] FIG. 4 is a perspective view of a transverse flux motor
stator and coil as well as a traditional stator.
DETAILED DESCRIPTION
[0035] The following description is of various exemplary
embodiments only, and is not intended to limit the scope,
applicability or configuration of the present disclosure in any
way. Rather, the following description is intended to provide a
convenient illustration for implementing various embodiments
including the best mode. As will become apparent, various changes
may be made in the function and arrangement of the elements
described in these embodiments without departing from the scope of
the appended claims.
[0036] As seen in FIG. 1, the disclosed technology is directed to a
high volume low speed fan (HVLS) 10 comprised of a transverse flux
motor 14 such as that manufactured by Electric Torque Machines of
Flagstaff, Ariz., fan blades 18 mounted to struts 16 and a
controller 22. Trust Automation, Inc. of San Luis Obispo, Calif.
manufactures an exemplary fan controller such as their fan
controller with model number C-2411-CG01. The disclosed technology
does not require a gear box to reduce the rotational speed of the
electric motor 14 or increase its output torque. FIG. 2 reveals an
embodiment of a transverse flux motor 14 that details the bearings
24 surrounding the drive shaft 26 as well as the stator 28 and
rotor 30 surrounded by the motor housing 31. FIG. 2 further reveals
the struts 16 extending outwardly for attachment to the fan blades
18. The motor embodiment depicted in FIG. 2 reveals a heat sink 34
as well as the components 36, including a drive 38 of a controller
40 and a drive boot 42. The controller 22 is shielded with a bottom
cover 44 to protect the individual components 36 and drive 38
against damage and the collection of dust on the controller 22
circuit board 38.
[0037] FIG. 3 reveals an embodiment of the fan controller 22 with
the bottom cover 44 removed. As best seen in FIG. 4, the transverse
flux motor 14 is distinctly different from conventional motors 50
in that transverse flux motor 14 uses simple toroidal coils 52 with
the stator 54 `wrapped` around the coil 52 while conventional
motors 50 usually require copper coils 56 that encircle individual
stator teeth 60. Conventional windings suffer from poor slot fill
and end turn inefficiencies that become worse as pole count
increases. By using a single toroidal coil per phase, transverse
flux motors enable high pole counts with very low winding
resistance. This results in motors that produce unusually high
continuous torque per size and weight, while matching or exceeding
industry leading peak torque output.
[0038] The use of a transverse flux motor allows for longer duty
cycles, increased efficiency, excellent thermal properties, and,
where current HVLS systems require larger conventional motors,
increased cost savings resulting from the ability to provide
matching torque requirements in a much smaller motor mass. In an
exemplary embodiment, the disclosed drive motor technology provides
torque in the 13 to 170 Newton-meter range with rotational speeds
in the range of from 50-220 rpm and is capable of operating at
temperatures approaching 60 degrees centigrade.
[0039] In another exemplary embodiment, centrifugal overheat
protection provides supplemental cooling. The advanced motor
control technology provides added cooling protection as the
programmed controller 22 may be set to slow the fan rotational
speed if the ambient temperature exceeds the rated temperature of
the motor for a period of time until the ambient temperature is
reduced by the air the fan moves. In another exemplary embodiment,
an impact or a significant imbalance condition in the HVLS may be
detected by a lateral acceleration resulting from the impact or
imbalance. It will be appreciated that there are a variety of ways
in which a signal from an accelerometer may be used to influence
the operation of a fan system. For instance, the signal from the
accelerometer may initiate a controlled deceleration sequence to
bring the fan system to a gradual and controlled stop.
Alternatively, the signal from the accelerometer may simply cause
the power supply to be disconnected from the motor.
[0040] Furthermore, to the extent that the sensitivity of the
accelerometer is adjustable, the fan system may be configured
whereby different conditions sensed by the accelerometer may
produce different results. Furthermore, any suitable alternative to
an accelerometer may be used, to detect any of the above noted
conditions or to detect other conditions.
[0041] Another embodiment of the fan may also include a motion and
angular shutdown feature. This safety feature is added in the event
an accident occurs or if the fan is operated in an unsuitable
application such as when cross winds are present. This feature
eliminates or greatly reduces the need to rely upon guy wires for
vertical and safe operations. In addition, voltage recognition
enables stocking of one unit for many different users. This feature
enables the use of a broad range of incoming voltages, such as
110V, 240V to include single or three phase installations. These
voltage variations are all recognized and the fan operation is
fully functional without changing parts or software programs.
[0042] Another feature of the preferred technology is blade size
recognition which enables stocking by vendors of one unit for many
fan sizes. This technology enables the same power unit (motor and
drive) to operate various blade lengths without software changes.
The fan blades rotational speed is adjusted by how much current is
sent to the motor via the controller 22, more current equals more
torque which relates to the resulting RPM that overcomes the
resistive torque created by the air friction drag on the blades 18.
Blade diameter verification works by applying a certain torque to
the blades, the torque that is applied will correspond with a
certain rotational speed for each blade diameter and the controller
22 will read the rotational speed and confirm that it is within
tolerance for the selected blade 18 diameter profile. If a shorter
blade is mounted to the fan, the applied torque would result in a
rotational speed that is faster than what is allowed by the
controller 22, resulting in a fault code that is displayed on the
wall mounted user input panel 76. Likewise, if blades that are too
long are mounted to the fan, the controller would relay a code
showing that the blades are not spinning fast enough to meet the
acceptable rotational speed limits set by at the controller 22.
[0043] The preferred embodiment utilizes a blade profile/program
that is selected through the remote control panel/user input panel
76 such as shown in FIG. 1. The auto blade detect feature operates
by applying the torque required to run the smallest blade diameter
at full speed. Once blades are turning at a constant rotational
speed this speed is measured and verified against a look up table.
Each blade length will turn at different rotational speed with this
applied torque and the controller 22 will set the appropriate blade
profile. Once the blade length is set, the blade diameter
verification feature will be running in the background to make sure
the blade rotational speeds are always within tolerance.
[0044] Another preferred feature is the data logger recording of
approximately the last 100 hours of operation of the fan to address
warranty issues and to provide trouble shooting assistance. The
controller also maintains a count of the hours of operation up to
50,000 hours. The vendor can then use the hour count feature
supplied with the controller to assess how many hours the fan has
been operating. This feature is very useful for warranty purposes,
for example at 30,000 hours of operation, the fan warranty expires.
Each vendor can choose the number of hours of operation at which to
terminate their warranty. In addition, software updates and
programming of the controller 22 are accomplished through
Bluetooth, the internet or a Modbus keypad. Sensor inputs to
include humidity 80 and temperature 82 sensors will allow the fan
to react automatically to maximize human comfort by automatically
switching from downward airflow (cooling) to upward airflow
(heating) based on the thermal conditions of the building. Lastly,
the fan controller and drive motor can undergo troubleshooting via
Bluetooth and an internet Modbus keypad/device. This feature
greatly reduces the need for a technician to be lifted to the fan
motor and controller to access the fan at the ceiling level for
initial trouble shooting.
[0045] The preferred embodiment of the disclosed technology can
also be integrated with a building management system wherein the
building management system integrates the fan with lighting,
heating and cooling systems, doors and other components connected
to the system. For example, should the building lighting system
generate excess heat creating a comfort problem for the occupants,
distributed sensors will sense the environmental change and relay
information to the controller to increase the fan speed and
increase air circulation. Likewise, should a door be left open and
the interior temperatures begin to drop the building heating system
working in concert with the fans will operate to maintain the
desired temperature in the structure.
[0046] Having shown and described various embodiments of the
present invention, further adaptations of the methods and systems
described herein may be accomplished by appropriate modifications
by one of ordinary skill in the art without departing from the
scope of the present invention. Several of such potential
modifications have been mentioned, and others will be apparent to
those skilled in the art. For instance, the examples, embodiments,
geometries, materials, dimensions, ratios, steps, and the like
discussed above are illustrative and are not required. Accordingly,
the scope of the present invention should be considered in terms of
the following claims and is understood not to be limited to the
details of structure and operation shown and described in the
specification and drawings.
* * * * *