Note: Descriptions are shown in the official language in which they were submitted.
AUTOMATED FAN INLET DAMPER CLOSURE APPARATUS
This application claims priority to US Provisional Application No. 62/935,137,
filed
November 14, 2019.
TECHNICAL FIELD
The present disclosure is directed to apparatus and methods for preventing
back flow
through centrifugal fans.
BACKGROUND
Air delivery systems for building ventilation may consist of several
centrifugal fans
operating in parallel, perhaps in an array (e.g., a bank or assembly) in order
to act together to
provide more airflow than one alone could provide to a common area, space or
shared
discharge plenum. At times, a fan in that array becomes inoperative due to
mechanical
failure, electrical
supply issues, or planned system functions (as but a few examples) while other
fans in that
array continue to operate. When one of the fans is not operating (i.e., is
inoperative), it may
be important to prevent the reverse flow of air (backflow) through the
inoperative fan.
Backflow (and the reverse pressure differential across the fan that causes it)
may occur when
the pressure downstream of the fan(s) is greater than the pressure upstream of
the fan. Such,
if not obstructed via a damper, may force air back through (in a reverse
direction) the
inoperative fan(s). This is, of course, undesired, as it may reduce pressure
downstream of the
fan (e.g., such that it is less than an intended, design pressure), among
possibly having other
negative impacts. Embodiments of the inventive technology may help to resolve
such
negative impact(s) by obstructing such backflow through an inoperative fan of
a fan array
while allowing (and not unacceptably impacting) "forward" flow when that fan
is operating,
in addition to having other applications. Note that the inventive technology
may even have
application to a centrifugal fan that is not in an array, but that may still
be susceptible to
undesired backflow when that fan is inoperative if its flowpath is not
obstructed at that time.
23495491
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Date Recue/Date Received 2023-07-04
The inoperative fan backflow problem has been known for some time and there
are
conventional approaches to its solution. But the use of conventional dampers,
for example, placed
at the inlet to the fans has the disadvantage of reducing fan performance
during normal operation
and increasing the noise of the fan due to flow disturbances created by the
damper. Certain
conventional approaches may also be either mechanically complex (e.g., by
requiring centrifugally
actuated linkages and springs to, e.g., move a damper from one
configuration/position to another)
or require external attachment at the fan inlet (or external actuating
assemblies), both of which can
reduce fan performance, lead to imbalance problems during fan rotation, and/or
increase noise.
Additionally, in certain designs, as explained below, cracks in the "head" of
the damper (part
nearest the inlet cone) may appear after certain long-term, low speed fan
operation. Embodiments
of the inventive technology seek to alleviate one or more of these problems.
Such cracking was an important driver of the research that led to this
invention. Indeed, in
a series of damper failures in the field, the (typically aluminum) dampers
were found to be cracking
at the corner nearest the damper support (e.g., the bearing of that support).
It was found that users
would run the fans at very low speeds for long periods of time, and at such
low operational speeds,
there is a significant reduction in airflow (and, as such, a reduction in
(forward) velocity pressure
against the damper) that is required to keep the damper sufficiently pressed
(fully seated) against
the fan wheel backplate. At such low airflow (and low velocity pressure), the
damper may rock on
the shaft due to the moment created by its own weight as the fan wheel turns.
Such causes the
aforementioned cracks. Also, at lower speeds in particular, the inertia of the
damper, and
insufficient friction between the damper and the backplate, may cause unwanted
rotational motion
of the damper relative to the spinning backplate, which may lead to unwanted
noise and abrasive
wear (ideally, the two will rotate together, at the same rotational speed
(RPM)). Embodiments of
the inventive technology disclosed herein seek to mitigate the cracking risk,
and reduce relative
motion between the damper and the spinning backplate during low speed
operation of the fan by
keeping the damper fully seated against rotatable componentry (e.g., back
plate) when the damper
is in open position with a magnetic force that is not so strong that it
prevents motion of the damper
from open to closed position when backflow occurs.
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Date Recue/Date Received 2020-07-30
SUMMARY OF ASPECTS OF THE INVENTIVE TECHNOLOGY
The present disclosure provides a device that, in particular embodiments, may
securely seat a damper (e.g., of the type shown in US Patent No. 10,436,207
(the '207
Patent")) against the back plate of the fan wheel under low flow conditions,
through use of a
magnetic coupler that does not unacceptably alter the basic operation of the
damper. The
present inventive disclosure may be used with or without a clutch (e.g., a
clutch as described
in the '207 Patent).
According to an aspect of the invention is a centrifugal fan comprising:
stationary fan inlet componentry that defines an opening through which fluid
enters
said centrifugal fan;
rotatable componentry established downstream of said stationary fan inlet
componentry, wherein, during fan operation, said rotatable componentry rotates
about a fan
axis in response to an applied torque, said rotatable componentry comprising
blades that
impel said fluid, and a central shaft;
an axially translatable flowpath closure damper that axially translates along
said
central shaft and that is reconfigurable from a closed position to a fully
seated open position;
a damper support that supports said axially translatable flowpath closure
damper so
that said axially translatable flowpath closer damper can axially translate
along said central
shaft; and
a magnetic coupler that, with a magnetic attraction force, couples said
axially
translatable flowpath closure damper to said rotatable componentry so that
when said axially
translatable flowpath closure damper is in said fully seated open position,
said axially
translatable flowpath closure damper is coupled with, and rotates with, said
rotatable
componentry,
wherein said magnetic coupler is configured so that a reverse pressure
differential
across said centrifugal fan overcomes said magnetic attraction force, allowing
said axially
translatable flowpath closure damper to decouple from said rotatable
componentry and
axially translate along said central shaft from said fully seated open
position to said closed
position.
According to a further aspect is a centrifugal fan method compiising steps of:
defining, with stationary fan inlet componentry, an inlet opening through
which fluid
enters a centrifugal fan;
3
Date Recue/Date Received 2023-07-04
rotating rotatable componentry of said centrifugal fan about a fan axis of
rotation,
with an applied torque generated by a motor, said rotatable componentry
established
downstream of said stationary fan inlet componentry, and including a central
shaft;
impelling said fluid with blades of said rotatable componentry to generate a
forward
velocity pressure;
supporting, with a damper support, an axially translatable flowpath closure
damper, so
that said axially translatable flowpath closure damper can axially translate
along said central
shaft;
moving, as a result of at least said forward velocity pressure, said axially
translatable
flowpath closure damper from a closed position to a fully seated open
position;
coupling, through use of a magnetic attraction force, said axially
translatable flowpath
closure damper to said rotatable componentry so that when said axially
translatable flowpath
closure damper is in said fully seated open position, said axially
translatable flowpath closure
damper is coupled with, and rotates with, said rotatable componentry;
continuing to rotate said rotatable componentry while said axially
translatable
flowpath closure damper is in said fully seated open position;
co-rotating said axially translatable flowpath closure damper with said
rotatable
componentry when said axially translatable flowpath closure damper is in said
fully seated
open position;
terminating said step of rotating rotatable componentry;
generating a reverse pressure differential across said centrifugal fan;
overcoming said magnetic attraction force with said reverse pressure
differential;
axially translating said axially translatable flowpath closure damper along
said central
shaft from said fully seated open position to said closed position; and
obstructing said inlet opening with said axially translatable flowpath closure
damper
when said axially translatable flowpath closure damper is in said closed
position.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a perspective view, from front and above, of a centrifugal fan,
with damper in
closed position, as may appear in at least one embodiment of the inventive
technology.
FIG. 2 shows a perspective view, from front and above, of a centrifugal fan,
with damper in
open position, as may appear in at least one embodiment of the inventive
technology.
FIG. 3 shows a cross-sectional view of a centrifugal fan, with damper in open
configuration,
3a
Date Recue/Date Received 2023-07-04
as may appear in at least one embodiment of the inventive technology.
FIG. 4 shows a perspective view of a central shaft, boss, and magnetic
coupler, inter alia, as
may appear in at least one embodiment of the inventive technology.
FIG. 5 shows a cross-sectional view from the side of a central shaft, boss,
magnetic coupler
and damper support, inter alia, as may appear in at least one embodiment of
the inventive
technology.
FIG. 6 shows a cross-sectional view from the side of a first magnetic element,
damper
support and boss, as may appear in at least one embodiment of the inventive
technology.
FIG. 7 shows a cross-sectional view from the side of certain components when
the damper is
in an open configuration, as may appear in at least one embodiment of the
inventive
technology.
FIG. 8 shows a cross-sectional view from the side of certain components when
the damper is
in an open configuration, as may appear in at least one embodiment of the
inventive
technology.
FIG. 9 shows a clutch as may appear in at least one embodiment of the
inventive technology.
FIG. 10 shows a cross-sectional view of a centrifugal fan, with damper in
closed
configuration, as may appear in at least one embodiment of the inventive
technology.
2349580.1
3b
Date Recue/Date Received 2023-07-04
DETAILED DESCRIPTION OF THE VARIOUS EMBODIMENTS OF THE INVENTION
It should be understood that the present invention includes a variety of
aspects, which may
be combined in different ways. The following descriptions are provided to list
elements and
describe some of the embodiments of the present invention. These elements are
listed with initial
embodiments; however, it should be understood that they may be combined in any
manner and in
any number to create additional embodiments. The variously described examples
and preferred
embodiments should not be construed to limit the present invention to only the
explicitly described
systems, techniques, and applications. The specific embodiment or embodiments
shown are
examples only. The specification should be understood and is intended as
supporting broad claims
as well as each embodiment, and even claims where other embodiments may be
excluded.
Importantly, disclosure of merely exemplary embodiments is not meant to limit
the breadth of
other more encompassing claims that may be made where such may be only one of
several methods
or embodiments which could be employed in a broader claim or the like.
Further, this description
should be understood to support and encompass descriptions and claims of all
the various
embodiments, systems, techniques, methods, devices, and applications with any
number of the
disclosed elements, with each element alone, and also with any and all various
permutations and
combinations of all elements in this or any subsequent application.
Embodiments of the inventive technology include apparatus that eliminate back
flow
through an inoperative/shutdown/never started centrifugal fan without complex
mechanical
linkages, external supports at the fan inlet, or actuators. In addition,
particular embodiments do not
reduce fan performance and may reduce fan noise by reducing turbulence in the
fan inlet 2. In
embodiments of the inventive shut-off apparatus, a closure damper 3 is
automatically "opened"
(moved to open position 6) by air flow through the fan 1 at some point in time
during the start
ramp (e.g., from 0 RPM to operating speed) of normal operation and stays open
during such
operation (including low flow/speed operation). When the fan is stopped,
sufficiently slowed, or
not started (e.g., related to failed or declining airflow into the fan inlet
due to power shutoff,
mechanical failure, startup failure, etc.) and there is generated a reverse
pressure differential 5
across that fan (which may be associated with a commencement of reverse flow
through the fan),
the damper may automatically move towards the closed position 7, and settle in
that position,
remaining there, seated in closed position 7, while a sufficiently large
reverse pressure differential
4
Date Recue/Date Received 2020-07-30
across the fan (e.g., as produced by other fans, perhaps operating in
parallel), exists. In the closed
position, the damper 3 may be held in place against stationary fan inlet
componentry (e.g., an inlet
cone) by this pressure differential.
The fan that may incorporate the magnetic coupler may be defined as including:
stationary
fan inlet componentry 4 (e.g., an inlet cone 8) that defines an opening 9
through which fluid (e.g.,
air) enters the centrifugal fan; rotatable componentry 10 (e.g., fan back
plate 11, fan blades 12,
support for fan blades 13, a central shaft 14, etc.) established downstream of
the stationary fan
inlet componentry 4, wherein, during fan operation, the rotatable componentry
rotates about a fan
axis 15 in response to an applied torque (applied by, e.g., a motor 16), the
rotatable componentry
comprising blades 12 that impel the fluid, and a central shaft 14; an axially
translatable flowpath
closure damper 3 that axially translates along the central shaft 14 and that
is reconfigurable from
a closed position 7 to a fully seated open position 6 (and back to the closed
position); and a damper
support 17 that supports the axially translatable flowpath closure damper 3 so
that it can axially
translate along the central shaft 14. The damper support may include a damper
bearing 18 that
allows the damper 3 to axially translate (via, e.g., sliding); such bearing 18
may also allow rotation
of the damper relative to the rotating central shaft 14 when co-rotation of
such components is not
desired (e.g., when the damper is in closed position). The damper support 17
may be rigidly
attached to the damper, such that whenever the damper rotates or translates,
so does the damper
support.
The inventive fan may include a magnetic coupler 20 that, with a magnetic
attraction force,
couples the axially translatable flowpath closure damper 3 with the rotatable
componentry 10 (e.g.,
with one of several rotatable components) so that when the axially
translatable flowpath closure
damper 3 is in the fully seated open position 6, the axially translatable
flowpath closure damper is
coupled with, and rotates with, the rotatable componentry 10. The magnetic
coupler 20 may be
configured so that a sufficiently large reverse pressure differential (perhaps
at least of a certain
value such as 0.6" WG, 0.4" WG, or 0.8" WG) across the centrifugal fan
overcomes the magnetic
attraction force, allowing the axially translatable flowpath closure damper 3
to decouple from the
rotatable componentry 10 and axially translate along the central shaft 14 from
the fully seated open
position 6 towards a closed position 7.
It is of note that the damper 3 may be attached around the central shaft 14 in
a manner that
allows it to translate along such shaft. Such attachment (e.g., sliding
attachment) may be allowed
Date Recue/Date Received 2020-07-30
for by a bearing 18 (a damper support, or part thereof) to which the damper 3
may be attached
(directly, or indirectly through intervening components), said bearing 18
established around the
central shaft 14 and allowing translatable motion (e.g., sliding), of the
damper support and the
damper, along, and possibly even rotation about, the shaft. Also, rotatable
motion of the damper
relative to the shaft may also be allowed for by such bearing (such relative
motion may be
detrimental when the damper is in its open position (sealed against the
rotating backplate), but
beneficial when the damper is in its closed position (sealed against the non-
rotatable inlet cone).
In certain embodiments of the inventive technology, during normal fan
operation (which
includes motorized low speed operation), the flowpath through the fan is open
(because the damper
is in open position 6) as shown in Fig. 2, with the damper 3 held against the
back plate 11 of the
fan by magnetic attraction force (and, likely, dynamic air pressure), The
axially translatable
flowpath closure damper (3) is, in certain embodiments, axisymmetric and of a
generally frusto-
conical shape formed from (but not limited to) preferably thin metal. The
motor proximate surface
21 (surface closest to the motor) of the larger diameter portion 22 of the
damper (the motor
proximate surface of the large diameter rim) may be configured (e.g., via
design and
manufacturing) so that it can rest securely (fully seated in open position 6)
against rotatable
componentry 10 (e.g., the back plate 11 of the fan). In some applications of
the damper, a gasket
of suitable material may be attached to such surface, The opposite surface 23
(e.g., motor distal)
of such rim may also be configured so that it can securely contact a surface,
i.e., the fan inlet cone
8 to effectively obstruct the flowpath through the fan and eliminate back flow
through the fan when
the damper is in its closed position 7.
The force of the damper against the rotatable componentry, as caused by the
magnetic
coupler 20 (and perhaps, to some degree, a forward velocity pressure), may
cause the damper 3 to
fully seat against that rotatable componentry 10 (e.g., fan back plate),
because such force is strong
enough to generate enough sufficient static friction between the damper
(perhaps including gasket
material as described elsewhere herein) and the rotatable componentry, so as
to prevent slippage
of the damper relative to that rotatable componentry. In certain embodiments,
the magnetic coupler
20 may be viewed as providing the additional force (i.e., possibly additional
to that force provided
by the forward velocity pressure) needed to fully seat the damper in its open
position 6, at low
speed operation of the fan (where velocity pressure is low, but where the
pressure differential
6
Date Recue/Date Received 2020-07-30
across the fan is either forward or, if reverse, is less than a certain value
(e.g., less than 0,6" WG,
0.4" WG, or 0.8" WG)),
The magnetic coupler 20 may comprise a first magnetic element 24 and a second
magnetic
element 25. The first magnetic element 24 may be configured (e.g., designed,
established, located,
positioned, manufactured) to translate with the damper 3 (typically it is
attached around the shaft,
in the vicinity of the portion of the damper that is nearest the shaft on
Which it translates, which is
typically the most narrow, central hole portion 26 of the damper, and the
portion of the damper
that is, for example, furthest from the backplate). It may be attached to the
damper support 17
(e.g,, the bearing 18) such that when the damper rotates and/or translates, so
does the first magnetic
element 24. The second magnetic element 25 may be established between the
portion of the
damper 3 that is nearest the shaft 14 on which it (the damper) translates when
the damper is in the
open position 6, and the portion of the shaft that is closest to the fan
backplate 11. In preferred
embodiments, the second magnetic element 25 does not translate with the damper
3; it is typically
attached so that it doesn't translate along the shaft (e.g., it may be affixed
to the shaft), and typically
(but not necessarily) rotates with the shaft. The magnetic coupler 20 may
couple the first magnetic
element 24 with the second magnetic element 25, and in doing so, may couple
the damper 3 with
rotatable componentry 10 (e.g., to the fan backplate 11), because the first
magnetic element 24
may be attached (directly or indirectly) to the damper, and the second
magnetic element 25 may
be attached to the rotatable componentry 10. Of course, the term coupler,
couple or coupling does
not require direct contact between two components to couple such components,
or when such two
components are coupled (although indeed there may indeed be such direct
contact).
The two magnetic elements 24, 25 are attracted towards each other, helping the
damper 3
achieve and stay in the fully seated open position 6 (where the damper's outer
rim 22 is fully seated
against, e.g., the backplate 11) during normal operation of the fan (where
normal operation
includes, inter alia, even low speed operation (e.g., low, but above 200 RPM)
that, by itself, might
not achieve a high enough airflow and velocity pressure to move the damper to
its fully seated
open position and/or keep it in such position). Indeed, in low speed
conditions (e.g., above zero
RPM but less than 200 RPM) where, without the magnetic coupler 20, the damper
3 might not be
fully seated against the backplate 11 or other rotatable componentry 10 (in
open damper position
6), the magnetic coupler 20 helps to achieve full seating of the damper 3
against, e.g,, the backplate
11, and thus helps to prevent not only the aforementioned rocking (that can
lead to cracks in the
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Date Recue/Date Received 2020-07-30
damper), but also, helps to prevent an undesired rotational motion of the
damper relative to the
spinning backplate (the magnetic coupler helps (at least) the damper to spin
with the spinning
backplate, without slippage), and/or rattling of the damper relative to the
backplate.
The first magnetic element 24 may be attached (as used herein, attached
includes direct or
indirect (e.g., through intervening part(s)) attachment) to the bearing 18 and
as such, that magnetic
element 24 may translate with the damper 3 as the damper translates along the
central shaft 14
(e.g., from open position 6 to closed position 7). Note that, as used herein,
terms such as coupled,
attached, affixed and connected include direct contact between the referenced
components, but
also indirect contact between the referenced components, where there may be
intervening part(s).
In certain preferred embodiments, the magnetic coupler is configured, whether
by size,
strength of the permanent magnet(s) and/or position (including relative
position) of its magnetic
elements (distance between them, if any, when the damper 3 is in open position
6), etc., so that the
magnetic pull force is strong enough to fully seat the damper 3 against
rotatable componentry 10
(e.g., the spinning backplate 11 of the fan 1) during operational flow of the
fan (e.g., flows
associated with a fan speed of at least 200 RPM (note that the low end portion
of operational flows
may be referred to as low operational speed flows)). Note that low operational
flows may also be
described as excluding flow associated with exceptionally low fan speeds,
e.g,, as excluding flows
associated with a fan speed below 200 RPM (or, e.g., excluding flows below 10%
maximum RPM
(two examples of max RPM are approx. 1980 RPM or 2550 RPM, each for a
different wheel
class)).
The magnetic coupler 20, in certain embodiments, is not so strong that the
damper will not
decouple, and leave its open position 6, breaking from and translating away
from the backplate 11
towards closed position 7, when a sufficiently high reverse pressure
differential across the fan (of
at least a certain value such as 0.6" WG, 0.4" WG, or 0.8" WG) occurs, at
which point, backflow
may be observed, Such reverse pressure differential may be caused by a
pressure downflow of the
fan that is greater than the pressure upflow of the fan. It may occur when the
fan stops operating,
e.g., stalls (and if the pressure downflow of the fan is high enough, such
backflow could occur
even before the fan fully stops spinning); it may occur when a fan of an array
fails to start or is
intentionally not started (perhaps when others in that array do start as
intended); it may occur below
a certain "forward" flow rotational speed of the fan (which might be observed,
e.g., at some point
after shutdown (motor power off), as the fan's speed slows from an operation
speed to zero). With
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Date Recue/Date Received 2020-07-30
this intentional configuration of magnetic pull force (e.g., via an
intentional design of the magnetic
coupler 20), the damper 3 is allowed to "break" the magnetic attraction force
holding it in a fully
seated open position 6, and move from that open position to a closed position
7, where it seals
against the inlet cone 8 (or other stationary fan inlet componentry 4), at a
predictable (approximate)
condition (e.g., a certain RPM or reverse pressure differential). Coupling and
decoupling may
occur at the same (roughly) RPM or reverse pressure differential, although
this is not required/may
not be observed. Closing the damper prevents backflow, may substantially
prevent significant
reverse rotation of the fan, and/or prevents loss of increased pressure (e.g.,
static pressure)
downflow of the fan, inter alia. Note that coupling (when the damper is in
open position) need
not, but certainly may, involve direct contact between the first magnetic
element and the second
magnetic element, Any space between such two elements may be observed when,
e.g., the damper
hits the backplate (or other rotatable componentry), and such prevents the two
magnetic elements
from contacting each other.
The magnetic coupler, in embodiments, could have components as follows:
- The first magnetic element 24 includes a first permanent magnet 27 (e.g.,
whether iron,
nickel, cobalt, or other known permanent magnet material, or material
including any one
or more of such materials in sufficient degree), and the second magnetic
element 25
includes a second permanent magnet 28;
- The first magnetic element 24 includes a permanent magnet 27, and the second
magnetic
element 25 includes a magnetic material 29 (e.g., iron, nickel, cobalt, or
other known
material that is attracted to a permanent magnet, or metals including any such
material(s)
in sufficient amount); or
- The first magnetic element includes a magnetic material 29, and the second
magnetic
element includes a permanent magnet 28.
Note that either or both of the first magnetic element and the second magnetic
element
could include a housing 30 in which the magnetic material or permanent magnet
is housed. Such
housing may, e.g., protect the permanent magnet and/or magnetic material
within it. The damper
may be directly attached to the first magnetic element (including, perhaps its
housing) and/or a
damper support (e.g., a bearing) to which the first magnetic element may be
attached.
Also of note is that, when the damper is in closed position, the fan may still
spin, perhaps
slightly, in the forward and/or reverse direction (due to back pressure and/or
turbulence downflow
9
Date Recue/Date Received 2020-07-30
of the fan ("pinwheeling")), but because of the bearing 18 (in certain
embodiments, attached to the
first magnetic element 24 (e.g., attached to the housing of the first magnetic
element)), the damper
3 will not spin with the shaft 14. And this is preferred, because then the
damper won't rub against
the stationary inlet cone 8 that it is sealed against in closed position
(which may cause abrasive
wear and make noise).
Fig. 10 (and Fig. 1) shows an exemplary centrifugal fan 1 and its associated
stationary fan
inlet componentry 4 (e.g., inlet cone 8), with damper in closed position. The
flowpath closure
damper 3, when in closed position 7, can be tightly held against the inlet
cone 8 to prevent back
flow through the fan. In particular embodiments, a bearing 18 can act as
damper support 17 to
support the damper 3; it and a central shaft 14 on which it may be established
can allow translation
(and rotation) of the damper 3 on central shaft 14. Allowing independent
rotation of the fan blades
12 relative to the damper 3 when it is in the closed position 7 prevents
abrasion and wear of the
damper against the fan inlet cone 8.
In certain embodiments, a central shaft 14 may be attached to bolts on the hub
of the fan
via a boss 31. A bearing 18 allows the damper 3 to translate and rotate on the
central shaft 14. A
magnetic coupler 20 may be attached to the bearing 18. A second magnetic
element 25 may
include, e.g., a ring of magnetic material 32; it may be fixedly attached to
the central shaft 14 and,
as one possibility, may be intentionally spaced a certain distance from a
first magnetic element 24
(e.g,, a permanent magnet) suitable to allow firm coupling of the damper 3
with rotatable
componentry 10 (e.g., the fan backplate 11), while also reliably and
repeatedly allowing for
movement of the damper from the open position 6 when there is, e.g., a
sufficiently high reverse
pressure differential (the damper, after the magnetic attraction force that
helps keep it in fully
seated open position breaks due to sufficiently high reverse pressure
differential that may cause a
reverse velocity pressure against the damper, can then translate to a closed
position 7).
Fig. 5 shows a detailed view of the magnetic coupler 20 as may appear in at
least one
embodiment. The coupler (including a portion thereof) may be attached (e.g.,
fixedly) to a
conventional bearing 18 to which the damper 20 may be attached (e.g.,
affixed). A metallic
material ring 32 may be attached (e.g., fixedly) to the central shaft 14. Such
ring, in certain
embodiments, is of magnetic material and provides an attractive target for
permanent magnet(s) in
the first magnetic element 24. The entire assembly (e.g., central shaft,
magnetic coupler, and
attached damper) may be attached to the fan wheel by a boss 31.
Date Recue/Date Received 2020-07-30
When the damper 3 is in the open position 6 against the back plate 11 of the
fan wheel
(as shown in FIG. 3 ), there is, in at least some embodiments, a gap between
the
first magnetic element 24 and the second magnetic element 25; such gap (e.g.,
along the
central fan axis) may be adjusted at assembly/manufacturing/retrofit to allow
the damper 3 to
lift from the fan back plate 11 in a predictable manner under conditions of
sufficiently high
reverse pressure differential (perhaps causing reverse flow), while still
coupling the
damper 3 with rotatable componentry 10 (and the first magnetic element 24 to
the second
magnetic element 25) during operating conditions, including nonnal, high, and
certain low
flow/RPM. Different fans, operating conditions, anticipated flows, pressures,
etc., may
benefit from different, customized coupler configurations (e.g., different
distances between
first and second elements of the coupler, different size, orientation and/or
strength of
permanent magnet(s), different size, orientation "magnetic attractiveness" of
magnetic
materials, which adjust the attractive magnetic force as desired) so that the
decoupling can
occur at the desired condition (e.g., at a certain reverse pressure
differential, backflow, or
even exceptionally low forward flow, or even no flow). As such, a magnetic
coupler may be
configured to decouple at a certain same reverse pressure differential. FIG. 5
shows a cross
section of the assembly shown in FIG. 4.
FIG. 6 shows a detailed view of the first magnetic element 24 and bearing 18
as they
may appear in certain embodiment(s). In the particular configuration
illustrated, the
first magnetic element 24 includes a ring magnet 33 (a permanent magnet),
which may be
held in place by a housing that includes an end cap 34, which itself may be
held by a number
of screws that attach the end cap to the bearing 18. As will be obvious to one
skilled the art,
there can be a number of methods of attaching a magnet to a bearing for the
purpose of
holding the damper 3 in place. Indeed, the first magnetic element 24, e.g.,
may include a
bearing within its housing. In addition, the permanent magnet and magnetic
material could
each be any shape, though a symmetric configuration and/or one where the
shapes may
correspond) may be preferable. Note that, as mentioned, the locations of the
first and second
magnetic elements may be reversed from what is shown in the figures.
Particular embodiments of the inventive technology include a clutch 35 (e.g.,
as
described in the '207 Patent) that causes the damper 3 to be engaged with
rotatable
componentry 10 at certain times (such as when the damper is in open position
6) so that the
damper rotates with that rotatable componentry when the damper is in open
position, and that
causes the damper to be disengaged from rotatable componentry at certain other
times (e.g.,
when the damper is in closed position) so that the damper does not rotate with
that rotatable
11
Date Recue/Date Received 2023-11-27
componentry when the damper is in closed position. In this way, the clutch 35
may be said to
couple the damper 3 with rotatable componentry 10 in open position 6 and
decouple the
damper from rotatable componentry in closed position 7 (note that when such
decoupling
occurs, the magnetic coupler 20 and the first and second magnetic elements 24,
25 are said to
decouple also). Additional aspects of the inventive technology relate to
methods, including a
related centrifugal fan method and a method of manufacturing an inventive fan.
Yet other
aspects relate to an inventive retrofit kit and related retrofit method.
Note that certain clutched designs may prevent rotational motion through
assistance
provided by a clutch (e.g., by clocking the damper (i.e., positioning it at
the same relative
rotational position, when in fully seated open configuration)); in such
designs, the primary
benefit of the magnetic coupler may be to keep the damper fully/securely
seated on the
backplate, and thereby prevent the aforementioned rocking that might otherwise
occur (e.g.,
during slower speed operation).
In certain embodiments, the closure damper 3 can be held in approximately the
same
angular location (relative to the fan wheel or other rotatable componentry)
when the damper
is in open position, via a clutch. This particular feature may minimize or
eliminate rotational
imbalance of the inventive fan otherwise caused by a varying rotational
position of the
damper. The clutch (e.g., as disclosed in the '207 Patent) may be used to fix
the rotational
position of the damper relative to the central shaft or other rotational
componentry (i.e., clock
the damper) when the damper 3 is in the open position 6. Clocking the damper,
when it is in
the open position, may be desirable when it is necessary to minimize
rotational imbalance of
the fan and damper. Clocking the damper when it is in the open position 6
maintains the
rotational balance of the entire fan assembly during normal operation. The
clutch, if present,
would disengage from the central shaft 14 when the damper 3 moves from open
position 6 to
closed position 7, thereby allowing the fan to freely rotate relative to the
damper 3 when the
flowpath closure damper is in the closed position 7.
Embodiments of the inventive technology may include a centrifugal fan method
that
may include the steps of: defining, with stationary fan inlet componentry 4,
an inlet
opening 9 through which fluid enters a centrifugal fan 1; rotating rotatable
componentry 10 of
the centrifugal fan
12
Date Recue/Date Received 2023-11-27
about a fan axis of rotation 15, with an applied torque generated by a motor,
the rotatable
componentry 10 established downstream of the stationary fan inlet componentry,
and including a
central shaft 14; impelling the fluid with blades 12 of the rotatable
componentry to generate a
forward velocity pressure; supporting, with a damper support 17, the axially
translatable flowpath
closure damper 3, so that it can axially translate along the central shaft;
moving, as a result of at
least the velocity pressure, the axially translatable flowpath closure damper
from a closed position
7 to a fully seated open position 6; coupling, through use of a magnetic
attraction force provided
by a magnetic coupler 20, the axially translatable flowpath closure damper
with the rotatable
componentry so that when the axially translatable flowpath closure damper is
in the fully seated
open position, the axially translatable flowpath closure damper is coupled
with, and rotates with,
the rotatable componentry; continuing to rotate the rotatable componentry
while the axially
translatable flowpath closure damper is in the fully seated open position; co-
rotating the axially
translatable flowpath closure damper with the rotatable componentry when the
axially translatable
flowpath closure damper is in the fully seated open position 6; terminating
the step of rotating
rotatable componentry 10; generating a (sufficiently high) reverse pressure
differential across said
centrifugal fan; overcoming the magnetic attraction force with the reverse
pressure differential
(e.g,, at at least 0,4, 0.6, or 0,8" WG reverse pressure differential) to
decouple the damper from
the rotatable componentry; axially translating the axially translatable
flowpath closure damper
along the central shaft from the fully seated open position to the closed
position; and obstructing
the inlet opening with the axially translatable flowpath closure damper when
the axially
translatable flowpath closure damper is in the closed position. The method may
involve the step
of decoupling the magnetic coupler (by decoupling the first magnetic element
24 from the second
magnetic element 25) at a certain same reverse pressure differential
(possibly, such reverse
pressure differential could, in certain embodiments, be adjusted (e.g., by
reducing or adding any
distance between the first and second magnetic elements and/or by changing the
position of either
or both of such elements on the central shaft)).
The method may further involve the step of clocking, with a clutch 35, the
axially
translatable flowpath closure damper 3 relative to the fan central shaft 14,
when the axially
translatable flowpath closure damper is in the fully seated open position 6.
In clutched designs, the
step of coupling an axially translatable flowpath closure damper 3 with the
rotatable componentry
may comprise the step of coupling, through use of a clutch 35, the axially
translatable flowpath
13
Date Recue/Date Received 2020-07-30
closure damper 3 with the rotatable componentry at any of a limited number of
angular locations
during each engagement.
The method may exhibit rotation of the rotatable componentry 10 without
rotating the
axially translatable flowpath closure damper 3 when the axially translatable
flowpath closure
damper is in the closed position 7. Obstructing the inlet opening 9 with the
axially translatable
flowpath closure damper comprises the step of sealing the axially translatable
flowpath closure
damper against the stationary fan inlet componentry 4.
Note that certain embodiments include a retrofit method whereby a damper,
central shaft,
magnetic coupler and bearing, all as described herein, are retrofit onto an
existing centrifugal fan.
In certain embodiments, this may be achieved by attaching an end of the shaft
to rotatable fan
componentry via attachment componentry such as screws and a boss.
As will be apparent to one skilled in the art, the angles, sizes and shapes of
the component
parts may be adjusted to meet requirements of specific fans without departing
from the spirit and
scope of the present disclosure. For example, the contours and shape of the
damper 3 may be
adjusted to accommodate the design details of a particular fan or to optimize
the air flow past the
damper. The design of the magnetic coupler may be modified to include a
variety of materials and
components.
As can be easily understood from the foregoing, the basic concepts of the
present invention
may be embodied in a variety of ways. It involves both flow obstruction
techniques as well as
devices to accomplish the appropriate flow obstruction. In this application,
the flow obstruction
techniques are disclosed as part of the results shown to be achieved by the
various devices
described and as steps which are inherent to utilization. They are simply the
natural result of
utilizing the devices as intended and described. In addition, while some
devices are disclosed, it
should be understood that these not only accomplish certain methods but also
can be varied in a
number of ways, Importantly, as to all of the foregoing, all of these facets
should be understood
to be encompassed by this disclosure.
The discussion included in this application is intended to serve as a basic
description. The
reader should be aware that the specific discussion may not explicitly
describe all embodiments
possible; many alternatives are implicit. It also may not fully explain the
generic nature of the
invention and may not explicitly show how each feature or element can actually
be representative
of a broader function or of a great variety of alternative or equivalent
elements. As one example,
14
Date Recue/Date Received 2020-07-30
terms of degree, terms of approximation, and/or relative terms may be used.
These may include
terms such as the words: substantially, about, only, and the like. These words
and types of words
are to be understood in a dictionary sense as terms that encompass an ample or
considerable
amount, quantity, size, etc. as well as terms that encompass largely but not
wholly that which is
specified. Further, for this application if or when used, terms of degree,
terms of approximation,
and/or relative terms should be understood as also encompassing more precise
and even
quantitative values that include various levels of precision and the
possibility of claims that address
a number of quantitative options and alternatives. For example, to the extent
ultimately used, the
existence or non-existence of a substance or condition in a particular input,
output, or at a particular
stage can be specified as substantially only x or substantially free of x, as
a value of about x, or
such other similar language. Using percentage values as one example, these
types of terms should
be understood as encompassing the options of percentage values that include
99.5%, 99%, 97%,
95%, 92% or even 90% of the specified value or relative condition;
correspondingly for values at
the other end of the spectrum (e.g., substantially free of x, these should be
understood as
encompassing the options of percentage values that include not more than 0.5%,
1%, 3%, 5%, 8%
or even 10% of the specified value or relative condition, all whether by
volume or by weight as
either may be specified. In context, these should be understood by a person of
ordinary skill as
being disclosed and included whether in an absolute value sense or in valuing
one set of or
substance as compared to the value of a second set of or substance, Again,
these are implicitly
included in this disclosure and should (and, it is believed, would) be
understood to a person of
ordinary skill in this field. Where the invention is described in device-
oriented terminology, each
element of the device implicitly performs a function. Apparatus claims may not
only be included
for the device described, but also method or process claims may be included to
address the
functions the invention and each element performs. Neither the description nor
the terminology is
intended to limit the scope of the claims that will be included in any
subsequent patent application.
It should also be understood that a variety of changes may be made without
departing from
the essence of the invention. Such changes are also implicitly included in the
description. They
still fall within the scope of this invention. A broad disclosure encompassing
both the explicit
embodiment(s) shown, the great variety of implicit alternative embodiments,
and the broad
methods or processes and the like are encompassed by this disclosure and may
be relied upon when
drafting the claims for any subsequent patent application. It should be
understood that such
Date Recue/Date Received 2020-07-30
language changes and broader or more detailed claiming may be accomplished at
a later date
(such as by any required deadline) or in the event the applicant subsequently
seeks a patent
filing based on this filing. With this understanding, the reader should be
aware that this
disclosure is to be understood to support any subsequently filed patent
application that may
seek examination of as broad a base of claims as deemed within the applicant's
right and may
be designed to yield a patent covering numerous aspects of the invention both
independently
and as an overall system.
Further, each of the various elements of the invention and claims may also be
achieved in a variety of manners. Additionally, when used or implied, an
element is to be
understood as encompassing individual as well as plural structures that may or
may not be
physically connected. This disclosure should be understood to encompass each
such
variation, be it a variation of an embodiment of any apparatus embodiment, a
method or
process embodiment, or even merely a variation of any element of these.
Particularly, it
should be understood that as the disclosure relates to elements of the
invention, the words for
each element may be expressed by equivalent apparatus terms or method
terms¨even if only
the function or result is the same. Such equivalent, broader, or even more
generic terms
should be considered to be encompassed in the description of each element or
action. Such
terms can be substituted where desired to make explicit the implicitly broad
coverage to
which this invention is entitled. As but one example, it should be understood
that all actions
may be expressed as a means for taking that action or as an element which
causes that action.
Similarly, each physical element disclosed should be understood to encompass a
disclosure of
the action which that physical element facilitates. Regarding this last
aspect, as but one
example, the disclosure of a "retainer" should be understood to encompass
disclosure of the
act of "retaining" ______________________ whether explicitly discussed or not
and, conversely, were there
effectively disclosure of the act of "retaining", such a disclosure should be
understood to
encompass disclosure of a "retainer" and even a "means for retaining" Such
changes and
alternative terms are to be understood to be explicitly included in the
description. Further,
each such means (whether explicitly so described or not) should be understood
as
encompassing all elements that can perform the given function, and all
descriptions of
elements that perform a described function should be understood as a non-
limiting example
of means for performing that function.
In addition, as to each term used herein it should be understood that unless
its
utilization in this application is inconsistent with a broadly supporting
interpretation, common
dictionary definitions should be understood and all definitions, alternative
terms, and
16
Date Recue/Date Received 2023-07-04
synonyms may be contained in the Random House Webster's Unabridged Dictionary,
second
edition.
Thus, the applicant(s) should be understood to have support to claim and make
a
statement of invention to at least: i) each of the automated flow obstruction
devices as herein
disclosed and described, ii) the related methods disclosed and described, iii)
similar,
equivalent, and even implicit variations of each of these devices and methods,
iv) those
alternative designs which accomplish each of the functions shown as are
disclosed and
described, v) those alternative designs and methods which accomplish each of
the functions
shown as are implicit to accomplish that which is disclosed and described, vi)
each feature,
component, and step shown as separate and independent inventions, vii) the
applications
enhanced by the various systems or components disclosed, viii) the resulting
products
produced by such processes, methods, systems or components, ix) each system,
method, and
element shown or described as now applied to any specific field or devices
mentioned, x)
methods and apparatuses substantially as described hereinbefore and with
reference to any of
the accompanying examples, xi) an apparatus for performing the methods
described herein
comprising means for performing the steps, xii) the various combinations and
permutations
of each of the elements disclosed, xiii) each potentially dependent claim or
concept as a
dependency on each and every one of the independent claims or concepts
presented, and xiv)
all inventions described herein.
The applicant has intended to capture as full and broad a scope of coverage as
legally
available for the claims. To the extent that insubstantial substitutes are
made, to the extent
that the applicant did not in fact draft any claim so as to literally
encompass any particular
embodiment, and to the extent otherwise applicable, the applicant should not
be understood
to have in any way intended to or actually relinquished such coverage as the
applicant simply
may not have been able to anticipate all eventualities; one skilled in the
art, should not be
reasonably expected to have drafted a claim that would have literally
encompassed such
alternative embodiment&
Further, if or when used, the use of the transitional phrase "comprising" is
used to
maintain the "open-end" claims herein, according to traditional claim
interpretation. Thus,
unless the context requires otherwise, it should be understood that the term
"comprise" or
variations such as "comprises" or "comprising", are intended to imply the
inclusion of a
stated element or step or group of elements or steps but not the exclusion of
any other
element or step or group of elements or steps. Such terms should be
interpreted in their most
expansive form so as to afford the applicant the broadest coverage legally
permissible. The
17
Date Recue/Date Received 2023-07-04
use of the phrase, "or any other claim" is used to provide support for any
claim to be
dependent on any other claim, such as another dependent claim, another
independent claim, a
previously listed claim, a subsequently listed claim, and the like.
Finally, the applicant expressly reserves the right to move any portion of or
all of the
content of the claims or any element or component thereof from the description
into the
claims or vice-versa as necessary to define the matter for which protection is
sought by this
application or by any subsequent continuation, division, or to obtain any
benefit of, reduction
in fees pursuant to, or to comply with the patent laws, rules, or regulations
of any country or
treaty, and shall survive during the entire pendency of this application
including any
subsequent continuation, division, or application thereof or any reissue or
extension thereon.
18
Date Recue/Date Received 2023-07-04
