Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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ROTARY FOAM DISTRIBUTOR
FIELD OF THE INVENTION
[0001] The present invention relates generally to fixed
piping fire suppression systems and, more particularly, to
a rotary-type foam distributor.
BACKGROUND OF THE INVENTION
[0002] A foam distributor is part of a fixed piping fire
suppression system capable of projecting a stream of fire-
extinguishing compressed-air foam or other compressed-gas
foam. In the art of firefighting, it is known to use foam
produced from a solution of a foam concentrate in water.
The volume of the solution is expanded by the addition of
air and mechanical energy to form a bubble structure
resembling shaving cream. The bubble suffocates and cools
the fire and protects adjacent structures from exposure to
radiant heat. Foam is known to be very effective on liquid
fires, e.g. fuel, oil or other flammable chemicals.
[0003] One current approach to covering large floor areas
is to use an oscillating nozzle to deliver the unfoamed
solution. As the solution is substantially unfoamed when
delivered, a more expensive agent is required and a higher
concentration of the agent (e.g. in the neighbourhood of 3
percent) is required. A greater volume of the solvent and
water are required to effectively cover the same area, in
comparison with systems that agitate the solution to
produce a thicker foam. This greater volume increases a
cost per use, requires a greater supply of water and
solvent (which can constitute considerable infrastructure
and costs), and greatly increases the cost of disposing of
the waste after a fire. Given that the delivery is across
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a semicircular arc, and that an array of these oscillating
nozzles are required to cover the large surface area, the
oscillating nozzle must be positioned only on the sides of
the building. Moreover, these devices typically require a
separate flow to provide the mechanical power to run the
device. These oscillating devices are therefore
inconveniently large, use 4-10 times more solution per unit
coverage area, cannot cover 360 degrees and are unsuitable
for other mounting configurations.
[0004] Foam can be generated using an air-aspirating
nozzle, which entrains air into the solution and agitates
the mixture producing bubbles of non-uniform size. With an
aspirating system, the foam is formed at the nozzle using
the energy of the solution stream. Unfortunately this
foaming typically removes substantially all of the
mechanical energy of the solution stream and consequently a
second flow is typically required to supply mechanical
energy needed to distribute the foam. The duplication of
supply, and the coordination of the two systems increases
an expense of the system and makes the system inherently
less reliable.
[0005] Foam can also be generated by injecting air under
pressure into the solution stream. The solution and air
mixture are scrubbed by the hose (or pipe) to form a foam
of uniform bubble size. The energy used in this system
comes from the solution stream and the air injection
system. This system produces a "compressed-air foam" (CAF)
which is capable of delivering the foam with a greater
force than a comparable aspirated system described above.
[0006] As is known in the art, compressed-air foam
distributors are installed on ceilings and walls for fire-
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protection in a variety of applications, such as in
warehouses and aircraft hangars. For example, in aircraft
hangars, ceiling-mounted or wall-mounted foam distributors
are poised to extinguish fires that might erupt if highly
flammable jet fuel is accidentally ignited. The
effectiveness of a distributor or a group of distributors
to fight a fire depends on a number of factors, such as
range or "reach", i.e. the distributor's ability to project
the foam an adequate distance, area coverage, i.e. the
floor space it can cover, reliability, compactness, power
efficiency, etc. Improving the effectiveness of a
distributor provides superior fire-suppression, thus
requiring fewer distributors to cover a given facility,
which accordingly reduces building costs and saves space.
[0007] As is known in the art, coverage can be improved
by rotating the nozzle of the distributor. A rotating
nozzle is described by Applicant in Canadian Patent
2,131,109 (Crampton) entitled "Foam Nozzle". This patent
describes a foam nozzle having a stationary barrel and a
rotary distributor with three tubular angled outlets.
Other rotating nozzles are described in Applicant's U.S.
Patents 6,328,225 and 6,764,024 (Crampton) both of which
are entitled "Rotary Foam Nozzle". These patents describe
an inverted-T-shaped rotary nozzle having a pair of
differently sized orifices in the rotating barrel for
distributing CAF in a circular pattern. Although these
distributors provide good fire-suppression coverage, it
would still be desirable to improve the effectiveness of
the rotary foam distributor to further improve its ability
to rapid suppress and control fires.
[0008] Furthermore, the distribution of compressed-air
foam from small (prior-art) rotary nozzles cannot be
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practically scaled up in size to cover large areas, as
scaling up in flow and size causes the rotational speed to
increase to unacceptable levels and does not significantly
increase the size of the coverage area. These prior-art
nozzles are thus restricted to applications that do not
require large areas of coverage. As is known by those of
ordinary skill in the art, the problem in extinguishing
flammable liquid pool fires in crowded aircraft hangars is
delivering the CAF to the floor, past obstructions such as
the wings or other vehicle bodies. Therefore, what is
needed to cover large floor areas with CAF is a distributor
that can deliver CAF to great radial distances with close
to flat horizontal projection. It is further desirable to
provide a distributor that has a low profile that permits
installation in recessed horizontal settings, such as in a
protected trough in a floor of the hangar.
(0009] Applicant's United States Patent 6,764,024
discloses an impeller-driven delivery system that uses
pressure of a CAF flow to drive an impeller, which is
coupled by an internally mounted gear box reducer within a
closed housing to revolve an output shaft that, in turn,
drives a diffuser. The diffuser is made to revolve to
distribute the CAF in a radial pattern.
(0010] Applicant has found that greatly improved transfer
of energy to a rotor, and a significantly more compact
assembly, can be achieved with a different configuration.
This configuration further provides a more robust, simpler,
impeller and transmission system that is better suited to
surviving extreme thermal and shock testing required of
such devices.
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[0011) Therefore, it would also be highly desirable to
provide a rotary foam nozzle that is compact, capable of
covering a full 360 degrees, supplies CAF that does not
require large water flow rates, does not require a
secondary power supply, can be mounted in multiple
configurations, and is robust.
SUI~IARY OF THE INVENTION
(0012] It is therefore an object of the present invention
to provide a foam distributor that overcomes at least one
of the deficiencies associated with the prior art as
described above. The foam distributor in accordance with
the present invention has an inlet for receiving foam from
a supply of compressed foam, such as compressed-air foam or
other types of fire-retardant foams. For example,
compressed gas foams can be made of concentrates and water
mixed with inert gasses, other than air. Upon entering the
distributor, the foam impinges on one or more vanes (or
other impingement surfaces) of an offset radial impeller,
wheel or rotor mechanism mounted on an input shaft, thereby
causing the radial impeller, wheel or rotor mechanism and
the input shaft to rotate. An offset radial impeller, as
used herein, denotes an impeller that revolves along an
axis that is transverse to the direction of flow, and so is
moved by the flow itself, and transverse movement of the
flow as it deflects radially away from a centre of rotation
of the impeller, which center of rotation being offset from
the direction of flow so that significantly less pressure
is applied to the impellers when not positioned within the
flow. The input shaft is geared to an output shaft upon
which is mounted a rotary outlet, which can be a diffuser
or a rotating vent of constant cross-sectional area. The
rotary outlet is thus rotated by the foam impinging on the
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vanes of the radial impeller, wheel or rotor mechanism. In
operation, foam is projected in a circular sweeping pattern
as the rotary outlet rotates relative to the distributor
body.
[0013] The distributor can be configured with a 90-degree
elbow or bend that diverts foam exiting a top surface of
the distributor body. The foam is diverted 90 degrees so
that foam is projected by the rotary outlet in a direction
of a hori zontal plane that is parallel to the inlet . The
rotary outlet can rotate over a full 360 degrees, providing
superior coverage for a large floor space, such as in
hangars or warehouses, using a quarter to a tenth of the
solution volume of conventional systems that do not foam
the solution. Being compact, and having a particularly low
vertical profile, this versatile distributor can be
installed in a floor trench of a hangar or on a wall or
ceiling. Since all rotational energy is harnessed from the
pressure of the foam itself, no external energy source is
required to power the distributor.
[0014] The rotary outlet can also be made to oscillate
rotationally over a limited arc by virtue of a
reciprocating mechanism in the gear train which constrains
the motion of the output shaft relative to the distributor
body. The angular velocity of the rotary outlet whether
freely rotating or oscillating may preferably be between 60
and 180 RPM. It has been found that slower angular
velocities, while providing for a longer reach of the foam
or delivering a greater volume of foam per unit area in
each pass, provides too much time between passes to
optimally extinguish some fires, and conversely faster
angular velocities tend to reduce the reach of the foam and
to cause discontinuities within the foam (depending on foam
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characteristics). To achieve this angular velocity, the
gear train may have a reduction ratio of between 6:1 and
30:1, which may best be produced with or without the
intermediary idler gear. It will be appreciated that these
figures may vary with flow properties of the foam,
properties of the impeller, and properties of the rotary
outlet, etc.
[0015] In accordance with an aspect of the present
invention, a distributor for distributing foam for
extinguishing a fire includes a distributor body having an
inlet for receiving foam from a compressed foam supply; a
rotor mechanism mounted for rotation within the body and
offset from the inlet, the rotor mechanism having
impingement surfaces against which foam impinges to cause
the rotor mechanism to rotate; and a rotary outlet
connected to the rotor mechanism for rotation of the outlet
relative to the body when foam impinges on the impingement
surfaces of the rotor mechanism.
[0016] In one embodiment, the rotary outlet is
rotationally connected to the rotor mechanism for
unconstrained 360-degree rotation of the outlet relative to
the body when foam impinges on the impingement surfaces of
the rotor mechanism.
[0017] In another embodiment, the rotary outlet is an
oscillating rotary outlet connected to the rotor mechanism
for oscillation of the rotary outlet relative to the body
through a limited arc when foam impinges on the impingement
surfaces of the rotor mechanism.
[0018] In yet another embodiment, the rotor mechanism
includesa radial impeller having a plurality of vanes
definingthe impingement surfaces, the radial impeller
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being mounted for rotation on an input shaft; and an output
shaft being operatively connected to the input shaft
whereby rotation of the input shaft causes rotation of the
output shaft, the output shaft being rotationally connected
to the rotary output.
[0019] In yet a further embodiment, the rotor mechanism
includes a radial impeller having a plurality of vanes
defining the impingement surfaces, the radial impeller
being mounted for rotation on an input shaft; and an output
shaft being operatively connected to the input shaft
whereby rotation of the input shaft causes rotation of the
output shaft, the output shaft being operatively connected
to the rotary output via a crank gear and push rod capable
of reciprocating an arm connected to the output shaft to
cause oscillation of the rotary output over a limited
angular range of motion.
[0020] In still a further embodiment, a gear chamber
isolation member is connected to the distributor body for
dividing an interior volume of the distributor body into an
enclosed gear chamber and a single, non-annular flow path
for the foam to traverse the distributor body without
interfering with the gear train.
[0021] In accordance with another aspect of the present
invention, a distributor for distributing fire-suppressing
compressed foam includes a distributor body having an inlet
for receiving foam from a compressed foam supply; an
impeller rotatably mounted within the body and offset from
the inlet, the impeller having a plurality of vanes against
which foam impinges to cause the impeller to rotate; and a
rotary outlet connected to the impeller for rotation of the
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outlet relative to the body, when foam impinges on the
vanes of the impeller.
[0022] In one embodiment, the impeller is mounted to an
input shaft geared to an output shaft to which the rotary
outlet is mounted.
[0023] In another embodiment, the input shaft is geared
to the output shaft to enable unconstrained 360-degree
rotation of the output shaft and rotary outlet relative to
the distributor body.
[0024] In yet another embodiment, the input shaft is
operatively connected to the output shaft via a
reciprocating mechanism to enable rotational oscillation of
the rotary outlet relative to the distributor body over a
limited arc of motion.
[0025] In yet a further embodiment, the rotary outlet is
mounted to an outlet shaft for rotation relative to the
body, the rotary outlet defining a rotating outlet chamber
external from the body, the rotating outlet chamber and the
body being in fluid communication via a plurality of exit
holes disposed around the output shaft at an interface of
the rotary outlet and the body.
[0026] In still a further embodiment, a gear chamber
isolation member is connected to the distributor body for
dividing an interior volume of the distributor body into an
enclosed gear chamber and a single, non-annular flow path
for the foam to traverse the distributor body without
interfering with the gear train.
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BRIEF DESCRIPTION OF THE DRAWINGS
(0027] Further features and advantages of the present
invention will become apparent from the following detailed
description, taken in combination with the appended
drawings, in which:
(0028] FIG. 1 is a bottom view of a rotary-type foam
distributor in accordance with a preferred embodiment of
the present invention;
(0029] FIG. 2 is a side cross-sectional view of the
distributor shown in FIG. 1 but further including a gear
chamber isolation plate;
[0030] FIG. 3 is a bottom view of a rotary-type foam
distributor having an oscillating rotary outlet in
accordance with another embodiment of the present
invention;
(0031] FIG. 4 is a side cross-sectional view of the
distributor shown in FIG. 3 but further including a gear
chamber isolation plate; and
(0032] FIG. 5 is a side cross-sectional view of the
distributor having a diffuser in accordance with yet
another embodiment of the present invention.
(0033] It will be noted that throughout the appended
drawings, like features are identified by like reference
numerals.
DETAILED DESCRIPTION OF THE PREFERRED EI~ODIMENTS
(0034] FIG. 1 is a bottom view of a rotary-type foam
distributor in accordance with a preferred embodiment of
the present invention. As illustrated in FIG. 1, the
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distributor, which is generally designated by reference
numeral 10, has a distributor body 12 (or housing) having a
foam inlet 14 for receiving foam, such as compressed-air
foam (CAF) or other compressed-gas foam. The incoming foam
travels along a foam entry axis 15 from a foam supply which
is not shown, but which is known in the art of fixed piping
fire-suppression.
[0035] Referring to both FIG. 1 and FIG. 2 (which is a
side cross-sectional view of the distributor), the
distributor 10 includes a radial impeller 16 (although
other equivalent devices include an impingement wheel or a
rotor mechanism) which, in turn, has a plurality of vanes
18 or impingement surfaces against which the foam impinges.
The radial impeller 16 is offset from the foam entry axis
15 so that impingement of the foam on the vanes of the
impeller causes the impeller to rotate. In other words,
the centre of the radial impeller 16 (as opposed to an
axial impeller taught in the aforementioned United States
Patent) is spaced apart or offset from the foam entry
axis 15, which is aligned to impinge upon the vanes 18.
This configuration effectively taps the energy of the CAF
flow, harnessing a small fraction of the available energy
but does not significantly reduce the range the CAF is
projected.
[0036] As shown in FIGS. 1 and 2, the radial impeller 16
is mounted to an input shaft 20 that is rotationally
secured within the distributor. Preferably, the input
shaft 20 is rotationally secured within bearings set in the
upper and lower surfaces of the distributor body to provide
smooth and efficient rotation of the input shaft 20
relative to the distributor body 12. The input shaft 20 is
operatively connected to an output shaft 28 via a gear
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train. Specifically in the preferred embodiment, a spur
gear 21 is mounted to the input shaft 20 beneath the radial
impeller 16. The spur gear 21 meshes with a first
intermediary gear 22 mounted on an idler shaft 24. A
second intermediary gear 23 mounted on the idler shaft
provides a gear reduction and meshing with an output gear
26 mounted on the output shaft 28. Therefore, rotation of
the input shaft 20 causes rotation of the output shaft 28,
albeit at a reduced angular velocity due to the reduction
gearing therebetween. The idler shaft and output shaft can
also be rotationally mounted in bearings to provide
smoother and more efficient rotation. For optimal
performance, depending on the surface area of the
impingement surfaces etc., the reduction gear ratio should
be between 6:1 and 30:1. This will generally ensure that
the angular velocity of the rotary outlet remains within a
desired band of about 60 to 180 RPM, although it will be
appreciated that CAF flow properties, dimensions and
configurations of the impingement surfaces, flow properties
in the area of the impeller, and other factors may change
the optimal gear ratio and/or angular velocities. Loose
meshing of the gears, as is well known in the art, permits
operation in a wide range of temperatures, accommodating
different thermal expansions of the respective components.
[0037] As shown in FIG. 2, the output shaft 28 is securely
connected to a rotary outlet 30 which is rotatable relative
to the distributor body. The rotary outlet 30 has a vent
or exit through which foam is projected as indicated by a
foam projection vector 32 in FIG. 2. Occasionally, the
rotary outlet 30 is referred to as a "nozzle" even if the
outlet does not have a converging cross-section in the
downstream direction. Optionally, the rotary outlet can be
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mounted on a bearing to provide more efficient rotation
relative to the distributor body.
[0038] In operation, when the fire-suppression system
incorporating the distributor 10 is triggered, compressed
foam is injected into the inlet 14. The foam impinges on
the vanes of the radial impeller, causing the radial
impeller to rotate and thereby causing the input shaft to
rotate. As the input and output shafts are geared
together, rotation of the input shaft causes the output
shaft to rotate, albeit at a lesser angular velocity, thus
causing the rotary outlet to also rotate relative to the
distributor body. Substantially simultaneously, the foam
injected into the inlet is forced under pressure through
the enclosure defined by the distributor body 12, and is
forced upwardly through a plurality of exits 34 into the
rotary outlet 30 where it is projected radially outwardly
in a circular sweeping pattern as the rotary outlet
rotates. In other words, in the preferred embodiment shown
in FIG. 2, the rotary outlet 30 can rotate 360 degrees in
an unconstrained manner relative to the distributor body to
cover a circular target area fully surrounding the
distributor.
[0039] As shown in FIG. 1, there are preferably five
equidistantly spaced exit holes 34 disposed
circumferentially around the output shaft 28. As will be
understood by those of ordinary skill in the art, the
number and shape of the exit holes 34 can be varied, and
other mechanisms for securing a rotating nozzle to a
distributor body that permit driving of the nozzle can be
used, subject to the strenuous demands of fire suppression
applications. For example, a chain drive can be used.
From FIG. 2 it should be apparent that the foam is first
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diverted ninety degrees from the horizontal to the vertical
by the distributor body and then ninety degrees back to the
horizontal by the rotary outlet. Persons of ordinary skill
will thus readily appreciate that various refinements can
be made to reduce pressure losses as the foam is forced
through the two successive ninety-degree turns. For
example, it is known in fluid mechanics to introduce smooth
bends or elbows to minimize the pressure drop.
[0040] As shown in FIG. 2, the rotary outlet 30 causes the
foam to divert ninety degrees so that the foam is projected
in a direction initially parallel to the foam inlet. In
other words, the projection vector 32 revolves in a
horizontal plane that is parallel to a horizontal plane of
the foam entry axis 15. The low-profile design of this
distributor is compact enough to be used in a variety of
tight spaces such as, for example, in a trench of an
aircraft hangar where foam can be projected under wings and
vehicle bodies to smother a ground-based fuel fire. The
distributor is compact enough to be used in a variety of
other applications as well, not only on the ground but also
on walls or ceilings.
[0041] FIGS. 3 and 4 illustrate a distributor 10 having an
oscillating rotary outlet in accordance with another
embodiment of the present invention. In this embodiment,
the radial impeller 16 is operatively connected to the
output shaft 28 (and hence to the rotary outlet 30) by an
oscillating mechanism 40 having a crank gear 42 meshed to
the spur gear 21 of the input shaft 20. The crank gear 42
is pivotally connected (at a first pivot 43) to a
reciprocating linkage such as a push rod 44. The push rod
44 connects at a second pivot 46 to an arm 48 fixed to the
output shaft. In operation, when the input shaft 20 is
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rotated by the foam impinging on the radial impeller 16,
the output shaft 28 (and hence the rotary outlet 30)
rotationally oscillates over a limited arc. In this
embodiment, the rotary outlet 30 oscillates back and forth
through an angle of about 170 degrees. This design is
particularly useful when the distributor is positioned near
a wall and the foam is delivered only to the target area
away from the wall.
[0042] In a preferred embodiment, as illustrated in FIGS.
2 and 4, the distributor 10 includes a gear chamber
isolation member, such as a gear chamber isolation plate
25, for isolating the gear train from the flow of CAF.
Although this component is not required, as is shown in the
embodiments of FIGS. 1 and 3, the gear chamber isolation
plate 25 is nevertheless helpful to preclude foam from
impeding the smooth movement of the gear train. The gear
chamber isolation plate 25 is also useful in situations
where rust, or other bodies may be present in the CAF. If
a large enough body were to become lodged in the gear
train, it will be appreciated that the gear train may
seize. By providing a gear chamber isolation plate 25 or
the like, interference with the gear train is precluded.
[0043] The input and output shafts may be supported by
bearings flush mounted to the upper and lower walls of the
distributor housing, bearings may be provided in a recess
of either the upper or lower walls of the distributor
housing, and/or the shafts may extend through one of the
upper and lower walls. Preferably, if a shaft extends
through a wall of the distributor housing, a shaft cover
plate 27, as shown in FIGS. 2 and 4 is provided to prevent
corrosion, or mechanical friction with anything below the
distributor housing. As will be appreciated by those of
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ordinary skill in the art, a plurality of shaft cover
plates covering individual shafts could also be utilized in
lieu of a single shaft cover plate, and numerous other
supportive and protecting configurations can be used as a
matter of design elective.
[0044] As further illustrated in FIGS. 2 and 4, the gear
chamber isolation plate 25 and the shaft cover plate 27 can
be affixed to the distributor body 12 by anchor rivets 29
or, alternatively, by screws, welding, or other fastening
means.
[0045] FIG. 5 illustrates another embodiment of the
distributor where the rotary outlet is a diffuser having a
diverging cross-section in the downstream direction. The
diffuser reduces the exit velocity of the foam but projects
the foam in an expanding cone rather than a cylindrical
"rope" of foam. As will be appreciated by those of
ordinary skill in the art, the rotary outlet can be a
diffuser, a constant-cross-section chamber, or a nozzle
depending on the desired projection characteristics.
Typically a constant cross-sectional area vent or diffuser
is preferable (and not a nozzle which restricts or
converges the foam as it exits). Likewise, where a
diffuser is used, its design should not cause undue
backpressure in the distributor which would stifle the
effective throughput of foam through the device.
(0046] As will be appreciated by those of ordinary skill
in the art, the distributor 10 must be constructed to
withstand high temperatures so as to be robust enough to
remain operable during a fire. A distributor of this
design may be able to withstand at least 600 degrees
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Celsius (1100 degrees Fahrenheit) for extended periods of
time, while in operation.
[0047] The distributor 10 harnesses the pressure of the
foam to drive the rotary outlet. Therefore, the
distributor is self-powered, which reduces installation and
operating costs and which also enhances the robustness of
the device. Furthermore, the distributor is highly
efficient in that it requires very little volume of water
and concentrate to cover a fixed area, relative to
comparably performing fire-suppression apparatuses. This
distributor requires only approximately one quarter to one
tenth of the solution of comparable wide-area prior-art
systems. Also, as noted above, the distributor is both
low-profile and capable of covering 360 degrees, which
makes it ideal for trench mounting.
[0048] Persons of ordinary skill in the art will
appreciate that variations or modifications may be made to
the distributor disclosed in the specification and drawings
without departing from the spirit and scope of the
invention. Furthermore, persons of ordinary skill in the
art will appreciate that the distributor described and
illustrated merely represents the best mode of implementing
the invention known to the Applicant; however, it should be
understood that other mechanisms or configurations, using
similar or different components, can be used to implement
the present invention. Therefore, the embodiments of the
invention described above are only intended to be
exemplary. The scope of the invention is limited solely by
the claims.
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