Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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: 20 BACKGROUND OF THE INVENTION
The invention relates to air distribution mecha~
nisms for directing air into a room in a uniformly
: distributed pattern and more particularly, to laminar
airflow diffusers intended to conduct air into a room
` ! 25 such as a clean room or operating room where it is
desirable to introduce a significant amount of highly
filtered air over the working area without significantly
disturbing the ambient air in the room and to provide a
low velocity blanket of air falling out of the ceiling
: 30 over a large surface area.
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Common air~low dif~u.sers h~ve included a plenum
with an inlet on one side, a perforated face plate on
the other side, and a variety of baffles, partitions,
pLates and the l-.ke thcrein to serve to distribute air
across the perforated face plate. These baffles are
intended to distribute the airflow so that the air
velocity leaving the perforated face is uniform across
the entire f2ce and also to direct air so that it
leaves the face in a vertical discharge pattern. The
prior art diffusers have been moderately effective at
obtaining uniform air distribution across the perforated
face but have failed to provide a consistent uniform
; discharge pattern.
Attention is directed to the Horneff et al.
15 patent, U.S. Patent No. 3,824,909, issued July 23, 1974
showing a plenum for discharging air downwardly into a
room through a perforated plate. No means are provided
,~ in the structure shown in the Horneff patent for
precluding airflow having horizontal components.
~`; 20 Attention is further particularly directed to the
Nesher et al. patent, U.S. Patent No. 3,303,771, issued
February 14, 1967, and showing another ventilated
ceiling construction including a plenum having a
specially formed perforated ceiling plate.
Attention is also directed to the Wilcox patent,
` U.S. Patent No. 3,986,850, issued October 19, 1976 and
the Moll et al. patent, U.S. Patent No. 3,638,404,
;~ issued February 1, 1972. These patents show alterna-
tive means for directing air into a room such as a
clean room, but show structures substantially unlike
that of the present invention.
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Other prior art dif~using mechanisms and ceilin~
structures are sho~n in the following patents:
Trader U.S. 1,554,180
Burns et al U.S. 3,200,734
Raider U.S. 3,301,163
Knab U.S. 3,314,353
Smith - U.S. 3,780,503
Smith et al ~.S. 3,782,082
Hazeley U.S. 3,892,170
~0 Cox U.S. 4,047,475
SUMMARY OF THE INVENTION
The structure of the invention overcomes the
shortcomings of the prior art and provides an improved
means of distributing the air flowing downwardly from
the ceiling and also of directing it into a vertical
flow pattern. The laminar airflow diffuser of the
invention also functions to allow a significantly
higher airflow per squaré foot of ceiling surface area
than is possible with the prior art structures without
significantly disturbing the ambient air in the room.
The invention provides a laminar airflow diffuser
for directing air into a room and for distributing air
over at least a portion of the ceiling of a room
uniformly and vertically downwardly. The airflow
diffuser includes a plenum whlch is positioned adjacent
the ceiling and which includes a chamber therein and an
inlet opening connectable to an airflow source. The
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plenum includes a perforated face plate having a
plurality of openings therein for conveyin~ air into
the room. Means are further provided for distributing
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the .lir rJeneraLly uniEormly throu~hout the plenum
chamber. The distributirl~ means ;ncludes a distribution
hafEle housed within the plenum chamber and connected
to the air inlet opening. The laminar airflow diffuser
alsn i~cLudes a plan~r distribution grid positioned on
the perforated face plate, the grid being formed by a
plurality of intersecting vanes to preclude horizontal
airflow adjacent the lower perforated wall.
Other features and advantages of the embodiment of
the invention will become known by reference to the
follo~ing description, to the appended claims, and to
the drawings.
BRIEF DESCRIPTION OF THE DRAI~JINGS
Fig. 1 is a cross-section elevation view of a
laminar airflow diffuser embodying the present invention.
Fig. 2 is a cross section view taken along line
2-2 in Fig. 1.
Fig. 3 is a cross section view taken along line
3-3 in Fig. 1.
Before explaining at least one embodiment of the
invention in detail, it is to be understood that the
invention is not limited in its application to the
details of construction and the arrangement of the
components set forth in the following description or
illustrated in the drawings. The invention is capable
of other embodiments and of being practiced and carried
out in various ways. Also, it is to be understood that
the phraseology and terminology employed herein is for
the purpose of description and should not be regarded as
limiting.
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DE~CI' IPTl(lN O~ T}~E PREFE.Rr~ED i::~!l3ODI~IENT
A lamina~ air~low di~Euser 10, shown in Fig. 1, is
intended to be positioned adjacent the ceiling of a
room such as an operating room or a clean room where it
is necessary to introduce a significant amount of
highly filtered air over the working area without
disturbing the air in the room. The laminar airflow
diffuser 10 is to be connected to an alrflow conduit 11
in turn co~municating with an airflow source 13 illus-
trated schematically. Since the details of the airmoving system are not necessary to an understandin~ of
this invention, they are not shown other than schematic-
ally.
The airflow diffuser 10 includes a plenum 12
defining a closed rectangular structure having an
upwardly extending central air inlet collar 14 connect-
able to the airflow conduit 11. The air inlet collar
14 is positioned centrally and projects upwardly from
an upper wall 15 of plenum 12. The plenum 12 also
includes downwardly extending side walls 16, the upper
wall 15 and side walls 16 defining a downwardly opening
plenum chamber 17. A horizontal perforated face plate
18 covers the lower end of the plenum chamber 17 to
provide for uniform distribution of air emitted from
the plenum chamber.
To provide for uniform distribution of the incoming
air throu~hout the interior of the plenum 12 and across
the entire surface of the perforated face plate 18, a
distribution baffle 20 is supported in the plenum
chamber 17 adJacent an air inlet opening 22 in the
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plenum 12 ~e~ined by the air inlet collar 14. ~i]e
the distribution ba~fle 20 can have various configura-
tions, in the illustrated construction, the
distribution baffle 20 comprises a rectangular housing
secured against the lower surface 24 of the upper wall
15 of the plenum 12 and surrounding the air inlet
opening 22. The rectangular housing is formed by a
horizontal bottom wall 26 and perforated side walls 28.
The bottom wall 26 is spaced upwardly from the perfo-
rated face plate 18 by a distance approximately egualto the vertical thickness of the distribution baffle
20. The side walls 28 of the distribution baffle 20
are also spaced inwardly of the side walls 16 of the
plenum 12. The upper edges of the side walls 28 are
surrounded by a flange 30 which extends outwardly
therefrom. The distribution baffle 20 is supported by
support brackets 32 secured to the lower surface 24 of
the upper wall 15 by screws 34, the brackets 32 engaging
the lower surface 36 of the flange 30 to support the
upper edges of the side wall 28 of the distribution
baffles 20 adjacent the upper waLl 15 and surrounding
the air inlet opening 22. Air flowin~ into the distri- -
bution baffle from the air inlet opening 22 will be
diffused as it flows through the perforated side walls
28 and will thus be distributed uniformly throughout
the plenum chamber 17 and across the surface of the
~; perforated face plate 18.
` In addition to providing means for causing even
`~ distribution of the air over a wide surface of the
perforated Eacc plate IB, means are rurther provided to
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cause Llir ~lowin~ throuo~h the openin&s in the perforated
face plate 18 to ~low vertically downwardly and al~so to
preclude horizontal velocity components in the airElow
in ~hat portion of the plenum chamber 17 adjacent the
perforated face plate 18. The airflow direction
controlling means includes a directional grid 40
positioned in the plenum chamber 17 and overlyin~, the
perforated face plate 18. The directional grid 40 has
an e~g crate, or lattice structure, formed by elongated,
narrow planar intersecting vanes 42. The intersecting
vanes 42 lie in intersecting vertical planes and form a
plurality of adjacent vertical channels 44 opening at
their upper ends into the plenum chamber 17 and being
closed at their lower ends by the perforated face plate
18.
The directional grid 40 is joined to the perfo-
rated face plate 18 and means are provided for securing
the directional grid 40 and face plate 18 to the side
walls 16 of the plenum 12 at its downwardly located
open end. While this supporting structure can have
various configurations, in the illustrated construc-
~:~ tion, L-shaped brackets 46 extend upwardly from the
: upper surface of the directional grid 40 and can be
;~ bolted by means of bolts 48 to complementary L-shaped
~; ; 25 brackets 50 secured to the inner surface of the side
~: walls 16 of the plenum 12.
The laminar air flow diffuser 10 described above
is an improvement over the prior art structures since
air emitted by the air flow diffuser is distributed
evenly from the face plate and is also directed verti-
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cally downwardly such that air flow from the grids
doesn't have horizontal directional components. A
laminar air flow diffuser of the invention has the
further advantage that ~reater volumes of air can be
S conveyed through the air flow diffuser without genera- ~
tion of turbulent air flow patterns. Each of these
advantages results from the combination of a plenum
having a lower perforated wall, a distribution baffle
positioned within the plenum chamber and for distribut-
ing air flow ~enerally uniformly throughout the plenum
! chamber, and a distribution grid positioned adjacent
the perforated wall fvr precluding horizontal airflow
in the plenum chamber adjacent the wall.
Various of the features of the invention are set
forth in the following claims.
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