U.S. patent application number 12/833653 was filed with the patent office on 2011-01-13 for air filtration system having a removable diffuser.
This patent application is currently assigned to Filtration Group, Inc.. Invention is credited to Edward F. Lyons, Wenli Wang, Philip J. Winters.
Application Number | 20110005178 12/833653 |
Document ID | / |
Family ID | 37499174 |
Filed Date | 2011-01-13 |
United States Patent
Application |
20110005178 |
Kind Code |
A1 |
Lyons; Edward F. ; et
al. |
January 13, 2011 |
AIR FILTRATION SYSTEM HAVING A REMOVABLE DIFFUSER
Abstract
An air filtration system includes a support structure, an
enclosure coupled to the support structure and including an air
outlet, a filter and a fan operatively coupled to the enclosure,
and a diffusion screen configured to cover the air outlet. The
diffusion screen includes a screen frame configured to be removably
attachable to the enclosure with at least one releasable fastener,
and at least a diffusion layer substantially spanning the screen
frame to cover the air outlet to provide unidirectional or laminar
air flow from the air outlet.
Inventors: |
Lyons; Edward F.;
(Riverside, IL) ; Wang; Wenli; (Woodridge, IL)
; Winters; Philip J.; (Lockport, IL) |
Correspondence
Address: |
MERCHANT & GOULD PC
P.O. BOX 2903
MINNEAPOLIS
MN
55402-0903
US
|
Assignee: |
Filtration Group, Inc.
Joliet
IL
|
Family ID: |
37499174 |
Appl. No.: |
12/833653 |
Filed: |
July 9, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11149019 |
Jun 9, 2005 |
7753977 |
|
|
12833653 |
|
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Current U.S.
Class: |
55/385.7 |
Current CPC
Class: |
B01D 46/0023 20130101;
B01D 46/10 20130101; B01D 46/0049 20130101; Y10S 55/29 20130101;
B01D 2265/028 20130101; F24F 3/163 20210101; B01D 2275/10
20130101 |
Class at
Publication: |
55/385.7 |
International
Class: |
B01D 46/42 20060101
B01D046/42 |
Claims
1-44. (canceled)
45. A mobile air filtration system comprising: (a) an enclosure
assembly comprising: (i) an enclosure including an air inlet and an
air outlet; (ii) a screen frame operatively coupled to the air
outlet of the enclosure; and (iii) a unidirectional flow screen
spanning the screen frame, the unidirectional flow screen having a
downstream side defined along a single plane, the unidirectional
flow screen covering the air outlet of the enclosure to result in
unidirectional filtered air flow; the unidirectional flow screen:
(1) including at least a single layer of material constructed and
arranged to provide unidirectional filtered air flow from the air
outlet such that filtered air flows in a single direction with
generally parallel air streamlines; and (2) creating only
unidirectional parallel air streamlines across the flow screen, to
shield an area from unfiltered air surrounding the area to result
in filtered air that travels further to the area with lower levels
of cross-contamination from particulates present in the surrounding
unfiltered air than filtered air from an air filtration system
without a unidirectional flow screen; (b) a mobile housing unit
comprising: (i) a housing having an air inlet and an air outlet,
the housing being movable relative to the enclosure; (ii) an air
filter positioned between the air inlet and outlet; and (iii) a fan
positioned within the housing; and (c) an air flow conduit
operatively connecting the mobile housing to the enclosure
assembly.
46. The mobile air filtration system of claim 45, wherein the
unidirectional flow screen comprises two layers of material.
47. The mobile air filtration system of claim 46, wherein the two
layers of material are a fabric material.
48. The mobile air filtration system of claim 47, wherein the
fabric material has a weave pattern.
49. The mobile air filtration system of claim 48, wherein the weave
pattern is a plain weave pattern.
50. The mobile air filtration system of claim 49, wherein the weave
pattern has pore sizes of no greater than 250 micrometers.
51. The mobile air filtration system of claim 49, wherein the weave
pattern has a nominal pore size of 150 micrometers.
52. The mobile air filtration system of claim 45, wherein the air
flow conduit is flexible.
53. The mobile air filtration system of claim 45, wherein the air
flow conduit is rigid.
54. The mobile air filtration system of claim 53, wherein the
mobile housing unit is located on a floor of a space served by the
air filtration system.
55. The mobile air filtration system of claim 54, wherein the
enclosure is supported by the rigid conduit.
56. The mobile air filtration system of claim 45, further
comprising a return air conduit connected to the air inlet of the
mobile housing unit.
57. The mobile air filtration system of claim 45, wherein the
filter is constructed and arranged to remove particulate matter,
gaseous matter, and/or contaminate matter.
58. An air filtration system for providing unidirectional filtered
air to a desired zone; the air filtration system comprising: (a) a
support structure; (b) an enclosure coupled to the support
structure and including an air outlet; (c) an air filter in
communication with the air outlet; (d) a fan operatively coupled to
the enclosure; (e) a screen frame; and (f) a unidirectional flow
screen spanning the screen frame, the unidirectional flow screen
having a downstream side defined along a single plane, the
unidirectional flow screen covering the air outlet to result in
unidirectional filtered air flow; the unidirectional flow screen:
(i) being spaced from and parallel to the air filter; (ii)
comprising multiple layers of polymeric fabric constructed and
arranged to provide unidirectional filtered air flow from the air
outlet such that air flows in a single direction with generally
parallel air streamlines; (iii) having a weave pattern having pore
sizes of no more than 250 micrometers; and (iv) resulting in only
unidirectional parallel air streamlines across the flow screen to
shield a work area from unfiltered air surrounding the work
area.
59. An air filtration system according to claim 58, wherein the
multiple layers include two layers of identical fabrics.
60. An air filtration system according to claim 58, wherein the
multiple layers include two layers of fabrics, with each layer
having a different pore size.
61. An air filtration system according to claim 58, wherein the
unidirectional flow screen has a first layer of fabric spaced 5/8th
inch from the air filter.
62. An air filtration system according to claim 61 wherein the
unidirectional flow screen has a second layer of fabric spaced
11/8th inch from the first layer of fabric.
63. An air filtration system according to claim 58 wherein the
multiple layers include two layers of different fabrics.
64. An air filtration system according to claim 58, wherein the
support structure is constructed and configured to be mobile.
65. An air filtration system according to claim 64, wherein the
support structure comprises a plurality of wheels.
66. An air filtration system according to claim 65, wherein the
enclosure is movable with respect to the support structure.
67. An air filtration system for delivering a unidirectional
filtered air flow to shield a work area from unfiltered air, the
air filtration system comprising: (a) a unit comprising: (i) a
support structure; (ii) an enclosure coupled to the support
structure and including an air outlet; (iii) an air filter housed
in the enclosure; (iv) a fan operatively coupled to the enclosure;
and (b) a unidirectional flow screen having a downstream side
defined along a single plane, the flow screen being positioned to
cover the fan filter unit outlet and spaced away from and parallel
to the filter, the unidirectional flow screen comprising: (v) at
least one layer of polymeric fabric having a weave pattern with
pore sizes of 50-250 micrometers, the at least one layer being
constructed and arranged to provide only unidirectional filtered
air flow from the fan filter unit across the flow screen such that
the filtered air flows to the work area in a single direction with
generally parallel air streamlines; (c) wherein cross-contamination
of the filtered air flow by particulates present in the surrounding
unfiltered air is less than that of an air filtration system having
a fan filter unit without a unidirectional flow screen.
68. An air filtration system according to claim 67, wherein the
filtered air flow is laminar and has a velocity of about 90 feet
per minute.
69. An air filtration system according to claim 67, wherein the
unidirectional flow screen is spaced 13/4 inches from the fan
filter unit filter.
70. An air filtration system according to claim 67, wherein the
support structure is constructed and configured to be mobile.
71. An air filtration system according to claim 70, wherein the
support structure comprises a plurality of wheels.
72. An air filtration system according to claim 67, wherein the
enclosure is movable with respect to the support structure.
Description
FIELD OF THE DISCLOSURE
[0001] The present application generally relates to air filtration
systems, and more particularly, to an air filtration system having
a removable diffuser.
BACKGROUND
[0002] Air filtration devices are typically used in environments
where clean air having low particulate matter or low gaseous
contaminate material is required. For example, air filtration
systems are used in operating rooms of hospitals, in hospital rooms
where burn patients are treated, in clean rooms such as
semiconductor manufacturing facilities, and in any other
environment where small particles, certain gaseous materials, or
certain contaminants in the surrounding air can be hazardous to a
person's health or disrupt the work being performed or damage the
products.
[0003] Air filtration systems typically include a fan unit that
receives air from an air input and directs the air with a desired
flow rate to a filter unit. The filter unit removes the particulate
matter and/or gaseous contaminant material from the air. Air
filtration systems may also include a diffuser positioned
downstream of the filter that can change flow characteristics of
the air. A diffuser can be designed to provide unidirectional flow,
multidirectional flow, laminar flow, or turbulent flow.
[0004] Many air filtration systems are of room air cleaner type.
They are designed to clean air in an entire room or space and can
not direct air to a small desired area. The air flow coming out of
a typical room air cleaner is turbulent. Such units cannot provide
unidirectional air flow to a specific zone to create a localized
clean environment.
[0005] Many other air filtration systems are ceiling mounted or
attached to a work surface. Accordingly, the clean air is directed
to a desirable location depending on the fixed position and
orientation of the air filtration system. For example, a ceiling
mounted air filtration system will typically direct the air flow
downward. In another example, a work bench can include an air
filtration system mounted above the work surface thereof so that
clean air is directed onto the work surface. Such air filtration
systems are not portable and can only be used in the environment
and for the application for which they are designed. Furthermore,
most of such air filtration systems do not have diffusers for
providing laminar or unidirectional clean air flow to a localized
zone without containment of the airflow. For those systems that
have diffusers, the diffuser can not be easily removed and replaced
with another diffuser. Such removal may be necessary for replacing
or cleaning the diffuser, or replacing the filter, or modifying the
flow characteristics.
[0006] Therefore, there exists a need in the art for an air
filtration system with a removable diffuser that is portable, can
be reoriented to provide unidirectional clean air to a desired
zone, and has a diffuser material that can be easily replaced or
cleaned.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Certain embodiments are shown in the drawings. However, it
is understood that the present disclosure is not limited to the
arrangements and instrumentality shown in the attached drawings,
wherein:
[0008] FIG. 1 illustrates a perspective view of an air filtration
system constructed in accordance with the teachings of the present
disclosure;
[0009] FIG. 2 illustrates a side view of another air filtration
system constructed in accordance with the teachings of the present
disclosure;
[0010] FIG. 3 illustrates a side view of another air filtration
system constructed in accordance with the teachings of the present
disclosure;
[0011] FIG. 4 illustrates a side view of another air filtration
system constructed in accordance with the teachings of the present
disclosure;
[0012] FIG. 5 illustrates a side view of another air filtration
system constructed in accordance with the teachings of the present
disclosure;
[0013] FIG. 6 illustrates a side view of another air filtration
system constructed in accordance with the teachings of the present
disclosure;
[0014] FIG. 7 illustrates a front perspective view of another air
filtration system constructed in accordance with the teachings of
the present disclosure;
[0015] FIG. 8 illustrates a side view of another air filtration
system constructed in accordance with the teachings of the present
disclosure;
[0016] FIG. 9 illustrates a perspective view of a diffusion screen
constructed in accordance with the teachings of the present
disclosure;
[0017] FIGS. 10(a) and 10(b) illustrate a perspective view and a
perspective exploded view, respectively, of a diffusion screen and
a corresponding fan and filter constructed in accordance with the
teachings of the present disclosure;
[0018] FIGS. 11(a)-11(d) illustrate perspective views of exemplary
diffusion layer configurations for a diffusion screen constructed
in accordance with the teachings of the present disclosure.
[0019] FIG. 12 illustrate a perspective view of a latching
mechanism for removably attaching a diffusion screen to an
enclosure in accordance with the teachings of the present
disclosure;
[0020] FIGS. 13(a) and 13(b) illustrate side views of two exemplary
configurations for the latching mechanism of FIG. 12; and
[0021] FIGS. 14(a)-14(c) illustrate side views of three exemplary
latching mechanisms for removably attaching a diffusion screen to
an enclosure and filter in accordance with the teachings of the
present disclosure:
DETAILED DESCRIPTION
[0022] For the purposes of promoting and understanding the
principles disclosed herein, reference will now be made to the
preferred embodiments illustrated in the drawings and specific
language will be used to describe the same. It will nevertheless be
understood that no limitation of the scope is thereby intended.
Such alterations and further modifications in the illustrated
device and such further applications are the principles disclosed
as illustrated therein as being contemplated as would normally
occur to one skilled in the art to which this disclosure
relates.
[0023] In accordance with a principal aspect of the present
disclosure, an air filtration system includes a support structure,
an enclosure coupled to the support structure and including an air
outlet, a filter and a fan operatively coupled to the enclosure,
and a diffusion screen configured to cover the air outlet. The
diffusion screen includes a screen frame configured to be removably
attachable to the enclosure with at least one releasable fastener,
and at least a diffusion layer substantially spanning the screen
frame to cover the air outlet to provide unidirectional air flow
from the air outlet.
[0024] In accordance with another principal aspect of the present
disclosure, a diffusion screen for an air filtration system having
a filter and a fan operatively coupled to an enclosure for
providing air flow from an air outlet of the enclosure includes a
frame and a diffusion layer. The frame is configured to be
removably attached to a perimeter of the air outlet with at least
one releasable fastener. The diffusion layer spans the frame to
cover the air outlet. The diffusion layer is configurable to
provide at least unidirectional or laminar flow from the air
outlet.
[0025] In accordance with another principal aspect of the present
disclosure, an air filtration system includes a support structure,
an enclosure coupled to the support structure, the enclosure
including an air outlet, a filter and a fan attached to the support
structure and operatively coupled to the enclosure to provide
airflow from the air outlet, and a diffusion screen configured to
cover the air outlet. The diffusion screen includes a frame
configured to be removably attached to a perimeter of the air
outlet with at least one releasable fastener, and at least a
diffusion layer spanning the frame to cover the air outlet, the
diffusion layer configured to provide at least unidirectional or
laminar flow from the air outlet.
[0026] Referring to FIGS. 1-7, several examples of an air
filtration system 30 constructed in accordance with the teachings
of the present disclosure are shown. Each of the air filtration
systems 30 includes a support structure 32 and an enclosure 34 that
is coupled to the support structure 32. The enclosure 34 includes
an air outlet 36. A filter and a fan (not shown) are operatively
coupled to the enclosure 34. Each of the air filtration systems 30
also includes a diffusion screen 40 that is configured to cover
their air outlet 36. The diffusion screen includes a screen frame
42 that supports at least one diffusion layer 44 substantially
spanning the screen frame 42. The screen frame 42 and the diffusion
layer 44 cover the air outlet 36 and provide unidirectional or
laminar air flow 46 from the air outlet 36.
[0027] The filter and the fan (not shown) may be housed in the
enclosure 34 such that it is adjacent to the air outlet 36.
Alternatively, the filter and the fan may be disposed outside the
enclosure 34 and in air flow communication with the enclosure 34.
The filter and the fan (not shown) are referred to herein as a
single unit. However, one of ordinary skill in the art will
appreciate that the filter and the fan (not shown) can also be two
independent structures that may only be in air flow communication.
Accordingly, the filter and the fan (not shown) that is disclosed
herein generally refers to any configuration of a filter and a fan
to provide the functionality disclosed herein.
[0028] The air filtration systems 30 may be portable. Accordingly
the support structure 32 may be coupled to a plurality of wheels 48
that can move the air filtration system 30 to any desired location.
Alternatively, the air filtration system 30 may be fixed and not
portable. For example, as shown in FIG. 6, the air filtration
system 30 may be installed in a ceiling of a room such that the air
outlet 36 is pointing generally downward into the room. As will be
described in detail in the following, FIGS. 1-7 illustrate several
exemplary configurations by which the air filtration system 30 may
be designed to provide unidirectional or laminar air flow from the
air outlet 36. Regardless of what type and configuration of air
filtration system 30 is used, the diffusion screen 40 can be
attached to the air outlet 36 of any air filtration system 30 so as
to provide unidirectional or laminar flow from the air outlet
36.
[0029] Referring to FIG. 1, the air filtration system 30 includes
the support structure 32 having a base 60, a pair of upright beams
62 and an upper support 64. The base 60 is supported on the ground
by the plurality of wheels 48 so that the entire support structure
32 can be portable. The enclosure 34 is attached to the upper
supports 64, such that the air outlet 36 is generally pointed
downward to provide the air flow 46 in the downward direction. The
length of the upright beams 62 may be adjustable to provide height
adjustability of the support structure 32. The enclosure 34 also
includes an air flow inlet 66 that provides air to the filter and
the fan (not shown) that is housed in the enclosure 34. The
diffusion screen 40 is attached to the enclosure 34, such that it
covers the air outlet 36 and provides the unidirectional or laminar
air flow 46. A pre-filter 49 (shown in FIG. 1) may also be disposed
in or outside the enclosure 34 to provide pre-filtering of the air
from the air flow inlet 66. Laminar flow is a state of flow where
fluid at low velocities flows without lateral mixing, which is
described mathematically by a Reynolds number. The adjacent layers
of flow slide past one another like playing cards. Laminar flow is
used in applications such as forming fog screen for image
projection or designing aircraft wings. Unidirectional flow is a
state of flow where fluid flows in a single direction with
generally parallel streamlines, which is not constrained by
specific Reynolds number ranges. Unidirectional flow is used in a
number of applications such as clean rooms for electronic and
pharmaceutical industries and biological safety cabinets where
process or products can be protected.
[0030] The diffusion screen 40 may include a plurality of
releasable fasteners 70 that can attach the diffusion screen 40 to
the enclosure 34. The enclosure 34 may be fixedly attached to the
upper support 64. Accordingly the direction of the air flow 46 may
not be adjustable. However, as shown in FIG. 4, the enclosure 34
may be pivotable relative to the upper support 64 or the upright
beams 62, such that the direction of the air flow 46 can be
adjusted as desired.
[0031] FIGS. 4, 7 and 8 illustrate two applications in which the
air filtration system 30 of FIGS. 1, 4, 7 and 8 can be used. The
air filtration system 30 can be used in medical facilities where
providing unidirectional or laminar air flow over a patient is
necessary to insulate the patient from the possibly unclean air in
the room. Accordingly, as shown in FIGS. 4 and 7, the air
filtration system 30 of FIG. 1 can be moved so that the enclosure
34 is either directly over a bed 65 in which the patient lies.
Also, as shown in FIG. 4, the enclosure 34 can be pivotally mounted
to the upright beams 62 at hinges 63 so as to adjust the direction
of the airflow 46 without having to move the air filtration system
30. Such a portable air filtration system 30 can be easily moved
throughout a medical facility.
[0032] Referring now to FIG. 8, another application in which the
air filtration system of FIG. 1 can be used is shown. In certain
work environments, it may be necessary to shield a work surface 67
from the air surrounding the work surface 67. Accordingly, the air
filtration system 30 of FIG. 1 can be moved so that the enclosure
34 is positioned over the work surface 67 and the air flow 46 is
directed generally downward onto the work surface 67. From the
above examples, one of ordinary skill in the art will appreciate
the numerous applications for which the disclosed air filtration
system 30 may be used.
[0033] Referring to FIGS. 2, 3 and 5, examples of an air filtration
system 30, where the filter and the fan (not shown) is disposed
outside the enclosure 34, are shown. The filter and the fan (not
shown) can be housed in a housing 71 that is supported on the
ground with a plurality of wheels 72. The housing 71 is an air flow
communication with the enclosure 34 by an air flow conduit 74. Air
flow from filter and the fan (not shown) flows through the air flow
conduit 74 to reach the enclosure 34 to then exit from air outlet
36 as the unidirectional or laminar air flow 46. The enclosure 34
may be supported by the air flow conduit 74. Accordingly, the air
flow conduit 74 may be rigid to provide such a support.
Alternatively, the air flow conduit 74 may be flexible such that
the enclosure can be supported by another structure to which it can
be attached.
[0034] The air filtration system 30 of FIG. 2 is portable and can
be moved to any desired location. As described above, the air
filtration system 30 of FIG. 2 can be used for numerous
applications where clean unidirectional or laminar air is desired
over a certain area. Referring to FIG. 5, if the enclosure 34 can
be supported in an elevated position, the air flow conduit 74 may
be flexible so as to provide more flexibility as to how the air
filtration system 30 can be used. For example, a flexible air flow
conduit 74 can provide pivoting of the enclosure 34 so that the air
flow 46 is directed to any desired location. Also, because the air
flow conduit 74 may be flexible, the housing 71 can be moved
relative to the enclosure 34. Such flexibility in the position of
the housing 71 with respect to the enclosure 34 and the variability
of the angle of the air flow 46 may be necessary in certain
applications. As shown in FIG. 5, the enclosure 34 can be mounted
over the work surface 67 to provide the air flow 46 generally
downward onto the work surface 67. Because the air flow conduit 74
is flexible, the housing 71 can be moved with the wheels 72 to any
location near the work surface that is allowed by the flexibility
and the length of the air flow conduit 74.
[0035] The air filtration systems 30 of the present disclosure may
also include an air conditioning device (not shown) to provide
conditioned air flow from the outlet 36. The air conditioning
device, which may be a typical air conditioning unit, a heater, or
a humidifier can provide temperature and relative humidity control
to the clean air for comfort. The air filtration system 30 may also
include a flow conditioning device to provide conditioned air flow
from the outlet 36. The flow conditioning device, which may be a
perforated plate or a series of straightening vanes, can modify the
air flow pattern prior to the diffusion screen to enhance the
effectiveness of the diffusion screen.
[0036] Referring to FIG. 3, any one of the air filtration systems
30 disclosed herein may include an air return 80 that may be
generally located opposite the air outlet 36 so as to capture the
air flow 46 and return the air flow 46 to the filter and the fan
(not shown). The air return 80 may be connected to the filter and
the fan (not shown) with a return air conduit 82. To support the
return air conduit 82, an air return support base 84 may be
provided. The air return support base 84 can be supported on the
ground with a plurality of wheels 86. Accordingly, the entire air
filtration system 30, including the air return 80 and the air
return conduit 82, can be portable and can be moved to any desired
location. The air return 80 can also be pivotable about the hinge
85. Accordingly, the air return 80 can be pointed in a direction so
as to capture a large volume of the air flow 46.
[0037] The air return 80 can include a pre-filter 87 to clean the
captured air prior to conveying the captured air back to the filter
and the fan (not shown). Instead of or in addition to the
pre-filter 87, the air return 80 can also include a perforated
plate 89. Because the air return 80 captures some if not most of
the air flow 46, the filter and the fan (not shown) will receive
substantially cleaner air than if outside air were drawn into the
filter and the fan (not shown) from an air inlet. Although the air
return 80 and the air return conduit 82 is shown with respect to
the air filtration system of FIG. 3 wherein the filter and the fan
(not shown) are in the housing 71 and not disposed in the enclosure
34, one of ordinary skill in the art will appreciate that the air
return 80 can be used for air filtration systems 30 such as those
shown in FIGS. 1, 4, 7 and 8 where the enclosure 34 also houses the
filter and the fan (not shown). If used with the air filtration
system of FIGS. 1, 4, 7 and 8, the return air conduit 82 can simply
connect the air return 80 to the enclosure 34 so that the air flow
46 can be captured and delivered to the filter and the fan (not
shown).
[0038] Referring to FIGS. 9 and 10, the diffusion screen 40 is
shown in more detail. The diffusion screen 40 is generally
configured to attach to the air outlet 36 and cover the air outlet
36 of any type of air filtration system including the disclosed air
filtration system 30. The diffusion screen 40 is attached to the
air outlet 36 of the enclosure 34 with one or more releasable
fasteners 70. The diffusion screen 40 includes the diffusion layer
44 and can be replaced when desired. Such a replacement may be
necessary when the diffusion screen 40 needs to be repaired,
cleaned or discarded and replaced with a new diffusion screen 40.
Additionally, such a replacement may be necessary when a diffusion
layer that provides a different air flow characteristic is desired.
As shown in FIG. 10, a gasket 90 can be disposed between the
diffusion screen 40 and the air outlet 36 so as to provide a
leak-free fit between the diffusion screen 40 and the enclosure
34.
[0039] Referring to FIGS. 11(a) and 11(d), several configurations
of the diffusion layer 44 are shown. The diffusion layer 44 can
include a single layer of a diffusion fabric 92 that includes a
weave pattern to provide the unidirectional or laminar air flow 46
out of the air outlet 36. As shown in FIG. 11(a), the diffusion
fabric 92 may be disposed at the bottom portion of the diffusion
screen 40 so that it is spaced apart from the filter (not shown).
In contrast, with reference to FIG. 11(b), the diffusion fabric 92
can be disposed at the upper part of the diffusion screen 40 so as
to be adjacent to filter (not shown). Referring to FIGS. 11(c) and
11(d), the diffusion layer 44 may also include several layers of
the same or different diffusion fabrics 92 to provide a desired air
flow 46 directed outward from the air outlet 36. For instance, the
diffusion fabric 92 could provide unidirectional or laminar flow
from the air outlet 36. The diffusion fabric may be replaceable so
that it can be removed for cleaning or replacement.
[0040] The releasable fastener 70 for attaching the diffusion
screen 40 to the enclosure 34 may be any type of fastener that can
provide releasable attachment. Referring to FIG. 12, an example of
a releasable fastener 70 as shown. The releasable fastener 70 can
include a latch 100 that is disposed on the frame 42 of the
diffusion screen 40. Enclosure 34 may include corresponding latch
keepers 102 so that the latches 100 engage the latch keepers 102
and can provide secure fastening of the diffusion screen 40 to the
enclosure 34, with the ability to release the diffusion screen 40
from the enclosure 34. Referring to FIGS. 13(a) and 13(b), two
examples of latches 100 and latch keepers 102 are shown. Referring
to FIGS. 14(a)-14(c), the latches 100 on the diffusion screen 40
may engage a feature of the enclosure 34 such as a lip or a flange
104. Three examples of such a lip or flange 104 are shown in FIGS.
14(a)-14(c). The latch 100 may include a hooked end 106 that can
engage with the lip or the flange 104 to secure the diffusion
screen 40 to the enclosure 34. The diffusion screen 40 may include
only one latch or a plurality of latches 100, and because the
enclosure 34 need not necessarily include latch keepers 102, the
latches 100 can engage a lip or flange feature of the enclosure 34
to fasten the diffusion screen 40 to the enclosure 34.
[0041] The diffusion layer 44 can have either a single layer of the
diffusion fabric 92 or multiple layers of the diffusion fabric 92.
The multiple layers of diffusion fabric 92 can be two layers of
identical fabrics, the same fabric with the same pore sizes, or it
can be two layers of the same or different fabrics with different
pore sizes. Several characteristics of the diffusion layer 44 can
influence the air flow 46. As described above, single or multiple
layers of diffusion fabric 92 and their corresponding pore sizes
can influence the characteristics of the air flow 46. Additionally,
the space between each diffusion fabric 92 and the space between
diffusion layer 44 and the filter (not shown) may also influence
the characteristics of the air flow 46. The pore sizes of the
fabric layers, the weave patterns, and the constituent materials of
each diffusion fabric 92 can be selected to provide specific flow
characteristics that are desired, such as a unidirectional flow or
laminar flow.
[0042] In one example of the diffusion screen 40, a one-layer
diffusion screen spaced 1-3/4 inches apart from filter face
performed better than when it was about 5/8 inch apart from filter
face. A two-layer diffusion screen with the 1st layer about 5/8
inch apart from filter face and about 1-1/8 inches apart from the
2nd layer underperformed a one-layer diffusion screen with layer
1-3/4 inch away from filter face. In another example of the
diffusion screen 40, a two-layer diffusion screen with two
different pore size layers can perform differently if switching the
1st and 2nd layers. When a plain weaved polymeric fabric sheet with
a nominal pore size of 150 micrometers is used in a single
diffusion layer screen, it demonstrated less lateral flow or better
unidirectional flow in flow visualization than a diffusion screen
using the same material with 250 micrometer pore size. Depending on
the application condition and desired flow, experiments with
various combinations of diffusion materials and layers can be
conducted to get an optimal or better setup. For instance, for air
flow rates of about 90 feet per minute at filter face, a one-layer
diffusion screen, made with plain weaved polymeric fabric with pore
sizes of around 50 to 200 micrometer range and spaced apart about
1-3/4 inches from filter face, may significantly improve the
unidirectional flow pattern. Therefore, the clean air can travel
much further to the desired area without containment due to minimal
cross-contamination than clean air from a filter without diffusion
screen. The above-described characteristics of the diffusion screen
40 are only exemplary and are not a limitation to the variety of
characteristics that can be employed to provide a desired type of
flow.
[0043] The disclosed air filtration. system 30 can be used in any
environment where removal of certain particles, gaseous matter, or
contaminate matter from the air is desired. The disclosed air
filtration systems 30 can be used in commercial and public
facilities such as clean rooms and hospitals. Additionally, the air
filtration systems 30 can be used in private homes for persons who
suffer from asthma, allergies, and emphysema. The portability,
small size, and the ability to remove the diffusion screen 40 for
cleaning, repair, or to change flow characteristics makes the use
of the disclosed air filtration system 30 possible for residential
and private use. However, one of ordinary skill in the art will
readily appreciate that the features and functions of the disclosed
air filtration system 30 also provide flexibility when used in a
commercial or public facility.
[0044] Furthermore, while the particular preferred embodiments have
been shown and described, it will be obvious to those skilled in
the art that changes and modifications may be made without
departing from the teaching of the disclosure. The matter set forth
in the foregoing description and accompanying drawings is offered
by way of illustration only and not as limitation. The actual scope
of the disclosure is intended to be defined in the following claims
when viewed in their proper perspective based on the related
art:
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