Note: Descriptions are shown in the official language in which they were submitted.
CA 02651612 2009-01-20
AIR DUCT CLEANING APPARATUS
This is a division of copending Canadian Patent
Application Serial No. 2,554,158, filed July 27, 2006.
TECHNICAT, FIELD OF THE INVENTION
[0001] The present invention is directed, in general, to an air
duct cleaning system and, more specifically, to an improved air
duct cleaning system for removing dust and debris from air
conditioning and heating ducts, dryer vent ducts, etc., of
residential and commercial buildings.
BACKGROUND OF THE INVENTION
[0002] So called "house dust" is widely considered by experts to
pose health hazards to persons with allergies, asthma, or
respiratory disorders and diseases. House dust may contain dirt,
textile fibers, pollen, hair, skin flakes, residue of chemical and
household products, cat and dog dander, decaying organic matter,
dust mites, bacteria, fungi, viruses, and a variety of other
contaminants. Literally, pounds of house dust accumulate on vents
and in ducts that comprise the ventilating systems of both
residential and commercial buildings. This house dust is becoming
increasingly more harmful as Americans spend a larger percentage of
their waking hours indoors, often aggravating allergies of the
inhabitants.
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[0003] Modern heating/ventilating/air conditioning (HVAC)
systems typically incorporate air filters either justprior to the
circulation fan of the systems or in the return ductwork. However,
most often these filters comprise fiberglass or similar media that
are reasonably effective against large debris, but are often
inadequate in removing fine particulate matter, such as dust,
dander, etc., from the circulated air. Such filters may trap as
little as twenty percent of the particulate matter circulating in
a ventilation system, allowing the remaining dust and debris to
circulate in the household or work place. A considerable after-
market industry has flourished providing both active and passive
electrostatic air filters. However, such filters only address
those particles in the air that pass through them after being
returned from the living space. The filter does not affect dust
and debris that is already present in the ducts downstream of the
HVAC unit that may be disturbed by airflow and carried into the
living space. Additionally, it is not uncommon to encounter
ductwork that has been improperly installed or maintained. These
ducts frequently leak, allowing dust and debris from the duct
surroundings to enter the ducts. Often this is a major contributor
to duct contamination.
[0004] Prior to the invention of duct vacuuming systems, one
method of addressing this problem was by sealing the dust and
debris to the inner walls of the ducts by coating it with a layer
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of a water-based resin, known in the trade as "duct sealer" or
"soot sealer". This compound is commonly used in fire restoration
of ventilating systems. After physically cleaning and sealing the
outflow registers, a hole is cut in the duct of the ventilating
system. An electric misting fogger is then mounted over the hole.
The fogger is activated and the soot sealer is dispersed throughout
the ventilating system. The soot sealer forms a coating over the
inner walls of the entire duct system, encapsulating dust and other
harmful impurities. Thus, the dust is not removed from the system,
but rather the sealant forms a new interior duct surface with the
dust trapped between the duct wall and the sealant surface. This
method has several inherent limitations. However, the drawbacks to
this system is its cost and the fact that the water based soot
sealer, given the right humidity conditions, may dissolve, thereby
freeing trapped dust and debris.
[0005] A more recent approach to the problem of debris in
ventilation ducts has been to use a rotating brush at the end of a
flexible vacuum hose that is fed into each duct from each register
location. The hose is fed toward the outflow portion of the HVAC
system to the limit of the hose length. Practically speaking, the
hose is usually about 25 feet to 35 feet long. Additionally, the
vacuum-generating units of these systems have been quite large and,
while mobile, were of such a size and weight that they are
impracticable to take into an attic. Yet, because of excessively
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long ductwork, it has sometimes been necessary to make multiple
entries along the duct system in order to completely clean the
ducts. It is sometimes impractical to properly clean the ducts of
modern homes with high, two-story ceilings with this system. Most
of the available hose would be used just to reach a register that
is 15 to 18 feet above the floor. Extending the hose by using
additional lengths was difficult because of the need to also extend
the brush drive mechanism throughout the additional lengths of the
hose. Additionally, thepe conventional systems, due to their
general configurations, may make it difficult to position the duct
cleaning machine close to the system being cleaned in order to
maximize use of available hose.
[0006) Accordingly, what is needed in the art is an apparatus
that offers a more flexible and mobile approach for cleaning HVAC
ducts.
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SUMMARY OF THE INVENTION
[0006a] Certain exemplary embodiments can provide an
apparatus for cleaning ducts of a heating/ventilation/air
conditioning (HVAC) system, comprising: a man-portable pod
having a vacuum chamber and a brush drive motor therein; a
flexible vacuum hose having a brush drive shaft contained
therein, an end of said brush drive shaft extending from an
interior of said flexible vacuum hose and removeably
coupleable to said brush drive motor; a conduit member
located within said man-portable pod and having a vacuum
chamber end and a vacuum hose end and an air path
therebetween, said vacuum chamber end in fluid communication
with said vacuum chamber and said vacuum hose end coupleable
to an end of said flexible vacuum hose; and a cart removably-
coupleable to said man-portable pod and configured to provide
rollable conveyance for said man-portable pod.
[0006b] Certain exemplary embodiments can provide a
method of cleaning a heating/ventilation/air conditioning
(HVAC) air duct, comprising: providing an apparatus for
cleaning ducts of an HVAC system, said apparatus including: a
man-portable pod having a vacuum chamber and a brush drive
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motor therein; a conduit member located within said man-
portable pod and having a vacuum chamber end and a vacuum
hose end and an air path therebetween, said vacuum chamber
end in fluid communication with said vacuum chamber; a
flexible vacuum hose having a conduit end and a duct end,
wherein said flexible vacuum hose has a rotatable brush drive
shaft extending from an interior of said flexible vacuum hose
at said duct end, and wherein said flexible vacuum hose is
coupleable to said vacuum hose end of said conduit member;
and a cart removably-coupleable to said man-portable pod and
configured to provide rollable conveyance for said man-
portable pod; and opening a service opening in a duct of said
HVAC system; uncoupling said man-portable pod from said cart;
transporting said man-portable pod -proximate said service
opening; and inserting said flexible vacuum hose through said
service opening and into said duct.
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[0007) Other embodiments provide an apparatus for
cleaning ducts of a heating/ventilation/air conditioning (HVAC)
system. In one embodiment, the present invention comprises a pod
having a vacuum chamber therein, a drive motor located within the
pod and configured to receive a removable drive shaft therein, and
a conduit member located within the pod adjacent the drive motor.
The conduit member has a vacuum inlet opening at an exterior wall
of the pod and a drive shaft exit opening formed in the conduit
member through which the removable drive shaft can extend. The
conduit member further includes a curve along an air path center
line of the conduit member, wherein the curve has an obtuse angle
taken from a center line normal to the vacuum inlet opening.
[0008] Other embodiments provide a man-portable pod
having a vacuum chamber and a motor therein, a conduit
member located within the man-portable pod and a cart removably-
coupleable to the man-portable pod. The conduit member has a
vacuum chamber end and a vacuum hose end and an air path
therebetween. The vacuum chamber end is in fluid communication
with the vacuum chamber and the vacuum hose end is coupleable to an
end of a flexible vacuum hose. The cart is configured to provide
rollable conveyance for the man-portable pod and attached hose
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including up and down stairs. A method of manufacturing the
apparatus and a method of cleaning an HVAC duct is also provided.
[0009] The foregoing has outlined preferred and alternative
features of the present invention so that those skilled in the art
may better understand the detailed description of the invention
that follows. Additional features of the invention will be
described hereinafter that form the subject of the claims of the
invention. Those skilled in the art should appreciate that they
can readily use the disclosed conception and specific embodiment as
a basis for designing or modifying other structures for carrying
out the same purposes of the present invention. Those skilled in
the art should also realize that such equivalent constructions do
not depart from the spirit and scope of the invention.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0010] For a more complete understanding of the present
invention, reference is now made to the following descriptions
taken in conjunction with the accompanying drawings, in which:
[0011] FIGURE 1A illustrates a top off-angle perspective view of
one embodiment of an improved apparatus for cleaning ducts of a
heating/ventilation/air conditioning (HVAC) system;
[0012] FIGURE 1B illustrates an exploded view of the air duct
cleaner showing the man-portable pod and the cart individually
[0013] FIGURE 2A illustrates a left side view of one embodiment
of the major internal elements of the man-portable pod;
[0014] FIGURE 2B illustrates a front oblique view of the major
internal elements of the man-portable pod of FIGURE 2A;
[0015] FIGURE 2C illustrates a rear view of the major internal
elements of the man-portable pod;
[0016] FIGURE 3A illustrates a rear elevation view of the
conduit member of FIGURE 2 including a hose attachment having the
vacuum inlet opening therethrough and located at a vacuum hose end
of the conduit member;
[0017] FIGURE 3B illustrates a rear elevation view of the
conduit member of FIGURE 2 with the hose attachment shown in FIGURE
3A removed;
[0018] FIGURE 3C illustrates a sectional view of the conduit
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member along plane 3C-3C shown in FIGURE 3B;
[0019] FIGURE 4 illustrates a front oblique view of the hose
attachment;
[0020] FIGURE 5 illustrates a rear oblique view of the major
internal elements of the man-portable pod and indicating an airflow
path through/around the major internal elements; and
[0021] FIGURE 6 illustrates a flow diagram for a method of
cleaning a residential/commercial HVAC system having an outflow
plenum.
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DETAILED DESCRIPTION
[0022] Referring initially to FIGUREs 1A and 1B, illustrated is
a top off-angle perspective view of one embodiment of an improved
apparatus 100 for cleaning ducts of a heating/ventilation/air
conditioning (HVAC) system. For the purposes of this description,
the apparatus 100 will henceforth be referred to as an air duct
cleaner 100. It should be understood that while the present
discussion is directed to HVAC ducts, the same equipment and
principles may also be used to clean other duct systems, e.g.,
dryer vent ducts, etc. The air duct cleaner 100 comprises two
principle elements: a man-portable pod 110, which is easily
removable from a cart 120. FIGURE 1B illustrates an exploded view
of the air duct cleaner 100 showing the man-portable pod 110 and
the cart 120 individually. Additionally, a flexible vacuum hose
140 having an internal flexible drive shaft 145, a vacuum nozzle
147, and a generally domal-shaped brush 150, are coupleable to the
man-portable pod 110. One who is of skill in the art is familiar
with the flexible vacuum hose 140 and brush 150 and their
application to duct cleaning.
[0023] In a preferred embodiment, the cart 120 is configured to
provide rollable conveyance for the man-portable pod 110 and the
flexible vacuum hose 140. The cart 120 comprises a cart body 121;
forward-mounted caster wheels 122 (only one visible); rear-mounted
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fixed wheels 123; left and right rear fenders 124, 125,
respectively; left and right front posts 126, 127, respectively; a
handle 128; a slot 131; and a first portion 132a of a latch 132.
In one embodiment, the latch 132 may be a barrel bolt. In a
preferred embodiment, the cart body 121 is made from a well known
durable, light weight molded plastic. In a preferred embodiment,
the cart body 121, left and right rear fenders 124, 125,
respectively; and left and right front posts 126, 127,
respectively; are molded as a single piece. The left rear fender
124 of the cart 120 has a groove 129 on an upper surface thereof.
Furthermore, the cart 120 has a declivity 130 from the left rear
fender 124 toward the left front post 126 located on a left front
corner of the cart 120. Both the groove 129 and the declivity 130
are sufficiently wide to support at least a portion of the flexible
vacuum hose 140 for coiled storage. The groove 129 is present on
the left rear fender 124 to provide a guide to an operator as the
flexible vacuum hose 140 is coiled around the pod 110 while
connected to a vacuum inlet ill of the man-portable pod 110.
Likewise, the left and right front posts 126, 127, respectively,
are positioned a distance d from the man-portable pod 110 and are
spaced sufficiently to receive the vacuum hose 140 therebetween.
As such, the pod 110 serves as a storage for the coiled vacuum hose
140, when the man-portable pod 110 is coupled to the cart 120. The
vacuum inlet opening 111 is proximate an exterior wall 115 of the
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man-portable pod 110 and is located higher up the exterior wall 115
than the prior art. This provides a better arrangement of the hose
140 that may now remain coiled about the man-portable pod 110 and
enables the air duct cleaner 100 to more conveniently be rolled up
and down stairs than the prior art.
[0024] In a preferred embodiment, the man-portable pod 110 is
also made of the same durable and light weight molded plastic as
the cart body 121. The man-portable pod 110 comprises: a handle
112, a rear shelf 113, a top cover 114, a cleat 116; and a second
portion 132b of the latch 132. The cleat 116 is configured to
cooperate with the slot 131 in the forward portion of the cart 120
to help secure the man-portable pod 110 to the cart 120.
Furthermore, the first portion 132a and the second portion 132b of
the latch 132 cooperate to removably couple the man-portable pod
110 to the cart 132. The handle 112 is coupled to the man-portable
pod 110 structure and configured to enable a technician to lift and
carry the man-portable pod 110 unattached from the cart 120, as
shown in FIGURE 1B. The rear shelf 113 is configured to support at
least a portion of the flexible vacuum hose 140 for coiled storage
between the man-portable pod 110 and the cart handle 128 when the
man-portable pod 110 is coupled to the cart 120. The top cover 114
provides a technician with access to the interior of the man-
portable pod 110 for changing disposable elements therewithin.
[0025] The unique configuration of the detachable man-portable
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pod 110 and the cart 120 allows for the man-portable pod 110 to be
easily removed from the cart 120 when tight attic spaces or
openings have to be navigated. As such, the main vacuum unit can
be taken proximate to the plenum so that the maximum length of the
duct, limited only by available hose length and not by HVAC system
configuration, can be reached. Therefore, the system provides for
a more thorough cleaning of the ventilation duct, as well as a time
savings. This is in distinct contrast to the conventional units
discussed above where, in many cases, the ventilation ducts had to
be cleaned from the registers because this unique pod/cart
configuration was not previously available in the art.
[0026] Referring now simultaneously to FIGUREs 2A-2C. FIGURE 2A
illustrates a left side view of one embodiment of the major
internal elements of the man-portable pod 110. FIGURE 2B
illustrates a front oblique view of the major internal elements of
the man-portable pod of FIGURE 2A. FIGURE 2C illustrates a rear
view of the major internal elements of the man-portable pod 110.
Elements of the duct cleaner 100 reside within the man-portable pod
110 (See FIGURE 1B). For example, a debris collection bag 211 is
positioned in an upper portion of the man-portable pod 110, which
makes it easily accessible by way of the top cover 114. The debris
collection bag 211 occupies a major portion of a vacuum chamber
212. A drive motor 213 is also located within the man-portable pod
110 adjacent the debris collection bag 211 but the drive motor 213
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is separated from the vacuum chamber 212 by a vacuum chamber wall
212a. A conduit member 214 extends from an outer wall of the man-
portable pod 110 to the debris collection bag 211, and as explained
below has a unique configuration that allows for greater air flow,
and thus, greater vacuum efficiency.
[0027] First and second vacuum motors 215a, 215b are located
underneath the debris collection bag 211 outside of the vacuum
chamber and are coupled to first and second filters 216a, 216b,
respectively. Moreover, they are configured to create a vacuum in
the vacuum chamber 212. The filters 216a, 216b are held in place
by first and second filter catches 217a (only the first filter
catch 217a is visible), which allows for easy removal of the
filters from the man-portable pod 110. An electronics control
board 218 is strategically positioned under the drive motor 213,
which allows air from the vacuum motors 215a and 215b to cool the
electrical components on the board. A friction clutch 219 is
coupled to a drive wheel 220 and a drive shaft 221 and these
components combine to drive a flexible drive shaft in the a vacuum
tube that is not shown. Those who are skilled in the art will
understand how an end of a flexible drive shaft may be configured
to couple to the drive shaft 221. In a preferred embodiment, the
drive motor 213 is a bidirectional drive motor 213.
[0028] In a preferred embodiment, the two vacuum motors 215a,
215b are employed in order to increase airflow through the system.
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The first and second filters 216a, 216b, are located within the
vacuum chamber 214 and are removably coupleable to the first and
second vacuum motors 215a, 215b, respectively. In a preferred
embodiment, the first and second filters 216a, 216b comprise HEPA
filters having a high filtering capacity. Additionally, they are
one-third larger (longer) than filters used in previous duct
cleaning apparatus. This allows for greater airflow through the
filters while using the same power of vacuum motor as in previous
systems. The first and second filter catches 217a, are coupled to
the man-portable pod 110 and are located proximate the first and
second filters 216a, 216b. The first and second filter catches
217a are configured to hold the first and second filters 216a,
216b, to the first and second vacuum motors 215a, 215b,
respectively.
[0029] Moreover, the filters 216a, 216b and filter catches 217a,
217b are configured to enable a technician to rapidly change the
filters 216a, 216b, yet hold the filters 216a, 216b securely
against the first and second vacuum motors 215a, 215b. The first
and second filter catches 217a, 217b are physically identical and
in a preferred embodiment, comprise flat spring steel bent to a
profile as illustrated with a tab 231 and a bend 232. Removal of
the respective filter 216a or 216b is accomplished by pulling the
tab 231 toward a front of the pod 110 until the bend 232 clears a
forward end 235 of the. filter 216a or 216b. The filter 216a or
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216b may then be rotated upwardly and decoupled at a rear end 236
from the respective vacuum motor 215a or 215b. A new filter 216a
or 216b may then be installed by placing the rear end 236 proximate
the respective vacuum motor 215a or 215b and rotating the new
filter 216a or 216b downwardly until bend 232 snaps into place on
the forward end 235.
[0030] Referring now simultaneously to FIGUREs 3A-3C for various
views of the conduit member 214 of FIGURE 2. FIGURE 3A illustrates
a rear elevation view of the conduit member 214 of FIGURE 2,
including a vacuum hose attachment 310 having the vacuum inlet
opening 111 therethrough and located at a vacuum hose end 331 of
the conduit member 214. Note that the conduit member 214 lies at
an angle a from a vertical reference line 320. FIGURE 3B
illustrates a rear elevation view of the conduit member 214 of
FIGURE 2 with the hose attachment 310 shown in FIGURE 3A removed.
Clearly shown is an opening 330 of the conduit member 214 at the
vacuum hose end 331 and proximate the vacuum inlet opening 111.
FIGURE 3C illustrates a sectional view of the conduit member 214
along plane 3C-3C shown in FIGURE 3B. The conduit member 214 also
has a vacuum chamber end 332 that is coupleable to the debris
collection bag 211.
[0031] The conduit member 214 has formed therein an air path 340
that is in fluid communication with the vacuum chamber 212 and has
an air path center line 311 that is a curve 313. The curve 311
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forms an obtuse angle 312 taken from a center line 311 normal to
the opening 330 and the vacuum inlet opening 111. In a preferred
embodiment, the obtuse angle 312 is about 139 . The conduit member
214 also has a drive shaft exit opening 314 formed in the conduit
member 214 through which a removable flexible drive shaft (not
shown) coupled to a rotatable brush (not shown) can extend. As can
be seen in FIGUREs 3A and 3C, the air path center line 311 forms a
compound curve 313 in that it includes two gently angled turns, as
shown in FIGURE 3C, and the plane of the centerline 311 is offset
from the vertical at an angle a. The obtuse angle of the compound
curve provides advantages over right-angled prior art
configurations in that the curved path allows for a greater
airflow, thereby providing for greater vacuum. In addition, the
gentle curvature of the conduit member 214 allows for greater
component density and strategic location of those components within
the man-portable pod 110. For example, the gentle curvature of the
conduit member 214 allows for the close placement of the drive
motor 213 and drive wheel 220, while, at the same time, providing
for a less restricted airflow path within the man-portable pod 110.
[0032] The drive shaft exit opening 314 is configured to receive
the removable flexible drive shaft of the rotatable brush therein.
By forming the conduit member 214 as shown, the flexible drive
shaft will exit the conduit member 214 low in the opening 330 as
far as possible from the air path centerline 311. This placement,
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as compared to prior art which exited the flow path at
approximately the air path centerline, allows minimal curving of
the air path 340 to clear the drive shaft exit opening 314 and the
drive wheel 220. Furthermore, as can be seen in FIGURE 3B, the
conduit member air path opening 330, preferably has an ovoid cross
section.
[0033] Referring now to FIGURE 4, illustrated is a front oblique
view of the hose attachment 310. The hose attachment 310 has a
conduit member end 401 and a hose end 402. The conduit member end
401 has a cross sectional shape necessary to couple to the opening
330 of the conduit member 214 (See FIGURE 3B). In the illustrated
embodiment, both the cross sectional shape and the opening 330 are
ovoid. This contrasts to a circular cross section of the hose end
402. Three rivets 411, 412, 413 enable push-and-twist coupling of
the vacuum hose 140 to the hose end 402.
[0034] It should be noted that a cross sectional area of the
conduit member end 401 is substantially greater than a cross
sectional area of the hose end 402. In a preferred embodiment, the
cross sectional area of the conduit member end 401 is about two
times the cross sectional area of the hose end 402.
[0035] Referring now to FIGURE 5, illustrated is a rear oblique
view of several of the internal elements of the man-portable pod
110. An airflow path 510 is indicated by the arrows through and
around the internal elements. The man-portable pod 110 further
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comprises an AC power connector 501, a master power switch 502, and
a mini-DIN receptacle 503. The AC power connector 501 is
configured to accept a removable three-conductor 110-115 VAC
equipment power cord (not shown for clarity) . The mini-DIN
receptacle 503 accepts a conventional mini-DIN plug 504
electrically coupled to a remote control 505.
[0036] The electronic board 218 is mechanically coupled to a
bottom cover 507 of the man-portable pod 110 proximate the drive
motor 213 and positioned with respect to the first and second
vacuum motors 215a, 215b to receive cooling air therefrom as shown
by the airflow path 510. The electronics board 218 is electrically
coupled to: the AC power connector 501; the master power switch
502; the mini-DIN receptacle 503; the remote control 505; the drive
motor 213; and the first and second vacuum motors 215a, 215b,
respectively. The remote control 505 uses only low voltage AC,
i.e., <1.0 VAC, electrical power derived from the 110/115 VAC power
by the electronics board 218. This is in contrast to prior art
that routinely uses 110/115 VAC line power at the remote controls
if they are so equipped. The use of low voltage AC electrical
power is preferred for improved component reliability of the
electronics board. The circuitry of the electronic board 218 is
configured to power OFF the air duct cleaner 100 if the mini-DIN
plug 504 becomes disconnected from the mini-DIN receptacle 503.
The air duct cleaner 100 cannot be powered up without connecting
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the mini-DIN plug 504 to the mini-DIN receptacle 503.
[0037] The electronic board 218 is electrically configured to
regulate one or more operations of the first and second vacuum
motors 215a, 215b or the drive motor 213. Specifically, the
electronic board 218 is configured to start the three motors 213,
215a, 215b in sequence so that the air duct cleaner 100 can be
readily used on commonly available electrical power on lighting
circuits of homes and businesses, i.e., 110/115 VAC from a duplex
wall outlet rated at 15 amps. One who is skilled in the art is
familiar with the fact that electric motors have a higher amperage
draw during startup than the amperage required for a steady running
state. The electronic board 218 accomplishes sequential startup of
the entire system by starting only one motor at a time thereby
limiting the startup amperage draw to that of only one AC motor at
a time. In most situations, it is advisable to start the vacuum
motors first, because if either or both of the vacuum motors are
inoperative, it is not desirable to run the drive motor with a
brush in a duct to prevent drive cable failure.
[0038] In practice, a start switch 521 on the remote control 505
is pushed. This starts a sequence of events on the electronic
board 218 that starts the first vacuum motor 215a which is sized to
be as powerful as possible without exceeding a total current draw
of all three motors of 15 amps. When the first vacuum motor 215a
is running stable, the electronic board 218 automatically continues
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the startup sequence by starting the secbnd vacuum motor 215b.
Only when both vacuum motors 215a, 215b are running stable, does
the electronic board 218 enable starting the drive motor 213.
After startup, the electronic board 218 is able to keep the total
current draw at all times below 15 amps, typically not exceeding
14.09 amps. This prevents repeated tripping of the circuit breaker
that would be common if all three, or even any two of the motors
were started simultaneously.
[0039] The electronic board 218 further includes a drive motor
213 reversing function. That is, the electronic board 218 may be
commanded to reverse the rotational direction of the drive motor
213 with a drive motor switch 522 on the remote control 505. The
drive motor switch 522 has three positions: ON (CW) -OFF-ON (CCW) . As
stated above, once the second vacuum motor 215b is running
normally, the drive motor switch 522 is enabled. Placing the drive
motor switch 522 to ON(CW) causes the electronic board 218 to start
the drive motor 213 to run with a clockwise rotation. Conversely,
placing the drive motor switch 522 to ON(CCW) causes the electronic
board 218 to start the drive motor 213 to run with a counter-
clockwise rotation. The electronic board 218 has additional
circuitry that causes the drive motor 213 to come to a "Full Stop"
whenever the drive motor switch 522 is moved to or passes through
the OFF position. This prevents the drive motor 213 from being
rapidly reversed, or accidentally stopped and then rapidly re-
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engaged, in order to protect the drive motor 213.
[0040] The electronic board 218 further includes a Maintenance
Only test kill function. That is, connections on the electronic
board 218 to selectively allow start and stop of either of the
vacuum motors 215a, 215b, independently of the operation of the
other vacuum motor. This enables a technician to isolate a vacuum
motor failure. This function operates independently of the drive
motor 213 circuitry and is not accessible with the air duct cleaner
100 in its normal operating configuration.
[0041] It should be noted that the combination of: (a) exit
location of the flexible drive shaft, (b) increased cross sectional
area of the conduit member end 401 versus the hose end 402, (c)
less abrupt change of direction of the air path flow, (d) increased
size of the HEPA filters 216a, 216b, and (e) dual vacuum motors
215a, 215b each individually, and collectively, contribute to an
increase in air flow by about 18 to 20 percent at the hose nozzle
147 (See FIGURE 1A), thus improving vacuum efficiency
significantly.
[0042] It should be noted that the present invention may be used
while the man-portable pod 110 is coupled to the cart 120.
However, a preferred method of operation of the air duct cleaner
100 is to clean a duct system from the vicinity of the main outflow
plenum of an HVAC system prior to the first branching of the ducts.
Referring now to FIGURE 6 with continuing reference to FIGUREs 1A
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through 5 as required, illustrated is a flow diagram 600 for a
method of cleaning a residential/commercial HVAC system 600 having
an outflow plenum.
[0043] The method begins at Start Step 605. At Step 610, the
air duct cleaner 100 is brought to the site having the HVAC system.
At Step 615, the man-portable pod 110 is decoupled from the cart
120. At Step 620, the man-portable pod is positioned proximate the
outflow plenum of the HVAC. At Step 625, a service opening is cut
or opened in the outflow plenum. At Step 630, a flexible vacuum
hose 140 with an internal flexible drive shaft 145 and attached
rotary brush 150 is coupled to the vacuum inlet 111 and to the
drive shaft 221 of the man-portable pod 110. At Step 635, the
rotatable brush 150 and portions of the flexible vacuum hose 140
and internal flexible drive shaft 145 are fed into the outflow
plenum through the access hole. At Step 640, the Start Switch on
the remote control is actuated.
[0044] At Step 641, the first vacuum motor 215a starts. At Step
642, the second vacuum motor 215b starts thereby making full system
vacuum available. At Step 643, the drive motor 213 is started,
thereby rotating the rotatable brush. At Step 645, the flexible
vacuum 140 and internal flexible drive shaft 145 are directed along
the outflow duct collecting debris from inside of the duct and
directing the debris along the flexible vacuum hose 140 to the
collection bag. At Step 650, the rotatable brush 150 arrives at a
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branch in the duct. At Step 655, the rotatable brush 150 is
directed along one branch of the duct system.
[0045] At Step 660, the operator decides if the duct being
cleaned is substantially wider than the brush. If the answer is
YES, then the method moves to Step 661 where the drive motor
direction is reversed to cause the brush 150 to work against an
opposite wall of the duct until Step 662 when the brush arrives
near an outlet register. If the answer is NO, the method proceeds
until step 662 when the brush 150 arrives proximate the outlet
register. At Step 663, the operator decides if all of the ducts
have been cleaned. If the answer is NO, then the operator
retrieves the brush 150 back to the previous branch of the duct.
At the branch and Step 665, the operator directs the brush 150
along a different branch of the duct and the method returns to Step
660. Steps 660 through 663 are repeated until all branches have
been cleaned. If the answer is YES, then the method proceeds to
Step 670 and the brush 150 is retrieved to the vicinity of the
access hole.
[0046] At Step 671, the drive motor 213 is stopped. At Step
672, the operator removes the flexible vacuum hose 140 and
rotatable brush 150 from the plenum. At Step 675, both vacuum
motors 215a, 215b are stopped. At Step 680, the service opening is
covered with a removable panel. At Step 685, the man-portable pod
is returned and coupled to the cart. At Step 690, the air duct
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cleaner is removed from the premises. At Step 695, the method
ends. One who is of skill in the art will recognize that
variations to the order in which various of the above steps occur
are within the broad scope of the present invention.
[0047] Thus, a duct cleaning apparatus and method of cleaning a
duct has been described. The duct cleaning apparatus comprises a
man-portable pod that is removable from a cart designed to provide
rollable transport for the man-portable pod and storage for the
accompanying vacuum hose.
[0048] Although the present invention has been described in
detail, those skilled in the art should understand that they can
make various changes, substitutions and alterations herein without
departing from the spirit and scope of the invention in its
broadest form.
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