Note: Descriptions are shown in the official language in which they were submitted.
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Background of the Invention
This invention relates to air mixing apparatus that
is particularly useful in connection with a winter make-up
air and a summer ventilation system for a factory, ware-
house or the like.
Ventilation and air circulating systems for
buildings are well known. Reference may be made, for
example, to the following U.S. Patents: 3,691,928 issued
September 19, 1972; 3,404,618 issued October 8, 1968;
3,446,272 issued May 27, 1969; 3,474,720 issued October
28, 1969; 3,747,501 issued July 24, 1973 and 3,524,399
~ issued August 18, 1970.
Generally speaking, such ventilation and air
circulation systems include some form of air
mixing apparatus that is capable of drawing air from
both inside the building and outside of the building
and a duct that is suspended from the roof
of the building and which is connected to the air mixing
apparatus to receive air therefrom. The duct has a plur-
ality of outlets along its length. Air at an appropriatetemperature, which depends upon the ratio of outside
and inside air that is drawn into the air mixing apparatus,
is forced into the duct and exits from the duct in the
area of the roof of the building. The result is that
smoke and fumes are diluted, stratification of heat and
foul air is eliminated, and air quality and temperature
are homogenized from floor to ceiling. The system is
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energy efficient, since waste heat adjacent the roof
area is forced down to the floor area. Another advantage
of the system is that the drawing in of fresh make-up
air eliminates negative pressure and stops the infiltration
of cold outside air and therefore drafts and cold spots.
A typical type of air mixing apparatus which
has been used in the past is shown in aforementioned
U.S. Patent 3,691,928. It is subject to a number of
disadvantages. More specifically, the
system shown therein is difficult to balance,
is subject to mechanical failure, and the dampers and
operating linkage therefor can freeze up during the winter.
Two different types of air mixing apparatus
are shown in U.S. Patent 2,313,676 issued March 9, 1943
lS and U.S. Patent 2,896,849 issued July 28, l9S9. The
disadvantage of the apparatus shown in U.S. Patent
2,896,849 is that it is relatively complex and requires
separate cold air and warm air ducts. The apparatus
shown in U.S. Patent 2,313,676 also is relatively complex
and requires two separate mechanisms for controlling
the ratio of outside air to recirculating inside air.
The prior art noted hereinbefore is the most
relevant prior art known to the inventor and assignee
of the instant application.
25Summary of the Invention
In accordance with the instant invention there
is provided air mixing apparatus that is mechanically
simple, is constructed of a small number of parts and
which avoids the disadvantages of the prior art air mixing
apparatus referred to hereinbefore.
In accordance with one aspect of this invention
there is provided air mixing apparatus comprising an outer
duct having side walls, an air inlet through which air
can be drawn into said duct, an air outlet through which
air can exit from said duct and at least one first port
in said side walls for passage of air into said duct;
an inner duct movably mounted within said outer duct,
said inner duct having side walls, said inner duct having
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at least one second port in said side walls of said inner
duct through which air can pass into said inner duct,
said inner duct also having an air outlet through which
air can exit from said inner duct, said air outlets of
said inner and outer ducts being in air-flow relationship,
whereby air exiting from said air outlet of said inner
duct then exits from said air outlet of said outer duct;
air baffle means extending between said outer and inner
ducts on either side of said at least one first port
and with said inner and outer ducts defining a header
into which air can pass through said at least one first
port; means for relatively moving said inner and outer
ducts back and forth between a first position and a
second position, in said first position said at least
one second port communicating in air-flow relationship
with said air inlet of said outer duct, whereby air
passes from said air inlet of said outer duct through
said at least one second port into said inner duc~ and
said side walls of said inner duct blocking flow of air
from said header into said inner duct, in said second
position said at least one second port communicating
in air-flow relationship with said header, whereby air
passes from said header through said at least one second
port into said inner duct, air flow from said air inlet
of said outer duct into said inner duct being blocked
by said inner duct and said baffle means, in intermediate
positions of said outer and inner ducts between said
first and second positions said at least one second port
having varying areas exposed to said header and to said
air inlet of said outer duct, whereby varying amounts
of air can be admitted to said inner duct via said at
least one second port from said air inlet of said outer
duct and from said header.
Brief DescriPtion of the Drawlngs
This invention will become more apparent from
the following detailed description, taken in conjunction
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with the appended drawings in which:
Figure 1 is a perspective view, partly broken
away, showing an air ventilation and circulation system
employing air mixing apparatus embodying the instant
invention;
Figure 2 is a longitudinal section through air
mixing apparatus embodying the instant invention; and
Figure 3 is a transverse section through the
air mixing apparatus.
Referring first to Figure 1, air mixing apparatus
1~ embodying the instant invention is shown as supported
from the wall 11 of a building 12. Air mixing apparatus
10 has an air inlet 13 for outside air and is connected
to a duct 14, which may be of polyethylene or the like,
and which is supported from the roof of building 12 in
a region adjacent to the roof. Duct 14 ex~ends across
the length of the building and, depending upon the width
of the building, more than one air ventilation and cir-
culation system of the type shown may be provided. There
are a plurality of outlets 15 in duct 14 through which
air from duct 14 exits into the interior of the building
adjacent the roof thereof.
Referring now to Figures 2 and 3, air mixing
apparatus 10 includes an outer duct 16 having side walls
17, an air inlet 13 through which air can be drawn into
the outer duct and an air outlet 18 through which air
can exit from the outer duct. It will be noted that
air outlet 18 is defined by a necked down section 19
of outer duct 16. This neck or flange 19 as well as
outer duct 16 preferably are cylindrical in configuration
to minimize the noise caused by air flowing through the
duct.
Provided in the side walls 17 of outer duct
16 are a number of ports 20 which, in the embodiment
shown, are of elongated configuration. However, the
shape and number of ports 20 may vary widely as long
as an opening or openings of sufficient size are provided
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for the required air flow. It should be noted that ports
20 communicate with the air inside of building 12.
Coaxially mounted within outer duct 17 is an
inner duct 21 which, preferably, also is cylindrical
5 in configuration. Inner duct 21 is movably mounted within
outer duct 17, as will become more apparent hereinafter.
Inner duct 21 has side walls 22 and an end wall 23. The
opposite end of inner duct 21 is open, however, defining
an air outlet 24 through which air can exit from inner
duct 21. Air outlets 18 and 24 are in air-flow relation-
ship, so air exiting from the air outlet of the inner
duct then exits from the air outlet of the outer duct
and, in this connection, there may be provided within
outer duct 17 a fan 25 driven by a motor 26 via a belt
27 and pulley 28, the latter being keyed or otherwise
fixed to the shaft 29 on which fan blades 25 are mounted.
For the sake of simplicity, the bearings for the fan
have not been shown.
Inner duct 21 has a number of ports 30 in its
side walls 22. Ports 30 are of the same configuration
as ports 20 and extend in spaced apart relationship with
respect to each other around the periphery of inner duct
21, just as ports 20 extend in spaced apart relationship
with respect to each other around the periphery of outer
duct 17. It will be noted that ports 30 are located
closer to the closed end of inner duct 21 than to the
open end thereof. Again the form and configuration and
the number of ports 30 may be varied as long as an approp-
riate area is provided for the required flow of air there-
through.
Two annular air baffles 31 and 32 with appropriateseals 33 extend between outer and inner ducts 17 and
21 respectively on either side of ports 20 and, with
the inner and outer ducts, define a header 34 into which
air can pass through ports 20.
The inner and outer ducts are capable of relative
longitudinal movement with respect to each other. In
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the embodiment as shown this is accomplished by means
of a motor 35 that drives a pinion 36 which engages a
rack 37 that is secured to inner duct 21. Inner duct
21 also is supported by toothed idler rollers 38 that
run in rack 37. Further support is provided by an upper
rail 39 secured to inner duct 21 diametrically opposite
from rack 37 and which runs in a track defined by two
brackets 40 that are secured to outer duct 17.
As best shown in Figure 3, hanger brackets 41
are secured to outer duct 17 to facilitate mounting thereof.
Inner duct 21 is movable between two positions,
one of which is shown in Figure 2. In that position
ports 30 communicate in air-flow relationship with air
inlet 13 of outer duct 17, permitting outside air to
pass from air inlet 13 of outer duct 17 through ports
30 into inner duct 21. In this position of inner duct
21 the side walls thereof effectively block the flow
of air from header 34 into inner duct 21, so that in
this position of the`inner duct, all of the air flowing
through air mixing apparatus 10 is drawn from outside
of the building. In the second position of the inner
duct, it is moved fully to the right in Figure 2. In
this position ports 30 communicate in air-flow relationship
with header 34~ so air passes from header 34 through
ports 30 into inner duct 21, and air flow from air inlet
13 of outer duct 17 is blocked by end wall 23 of inner
duct 21 and baffle 31.
Inner duct 21 can assume intermediate positions
between the two extreme positions hereinabove noted.
In these intermediate positions ports 30 will communicate
in part with header 34 and in part with air inlet 13,
whereby the ratio of outside to inside air may be varied.
The degree of variation normally is controlled by a thermo-
stat located in duct 14. The thermostat senses the tem-
perature of the air in the duct and controls motor 35to provide a proper ratio of outside air to inside air
to maintain a certain predetermined temperature of air
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in duct 14.
It will be noted that the primary components
of the air mixing apparatus of the instant invention
are cylindrical in configuration, at least in the pre-
ferred embodiment. This is desirable from the pointof view of minimizing the noise of air flowing through
the apparatus.
While a preferred embodiment of the instant
invention has been disclosed herein, those skilled in
the art will appreciate that changes and modifications
may be made therein without departing from the spirit
and scope of this invention as defined in the appended
claims.
