U.S. patent number 3,650,318 [Application Number 05/091,072] was granted by the patent office on 1972-03-21 for variable volume constant throw terminal re-heat system.
Invention is credited to Gilbert H. Avery.
United States Patent |
3,650,318 |
Avery |
March 21, 1972 |
VARIABLE VOLUME CONSTANT THROW TERMINAL RE-HEAT SYSTEM
Abstract
A system for temperature conditioning the air of a room in a
building. The system is particularly directed towards eliminating
drafty conditions and/or uncomfortable temperature variations,
predominantly noticeable heretofore as the typically conventional
system cycles during the summer months in operable response to a
thermostatic switch located in the room. Some of the features of
the present invention contributing towards the accomplishment of
the above include structure for by-passing variable volumes of the
supply air away from the room while forcing the remaining volume of
air into the room with the same velocity as when the total volume
of air was directed into the room, structure for re-heating a
portion of the aforementioned reduced volume of cool air so that
the confluence of cooler air and re-heated air is forced into the
room, again with the same velocity as when the total volume of cool
air was directed into the room, and structure for admitting varying
volumes of re-heated air into the room, i.e., up to 100 percent
re-heated air, for warming an overcold room, e.g., a room having
been cooled to a comfortable summer daytime temperature which is
considered too cool for comfort in the evening or nighttime, and
for heating the room during the winter months.
Inventors: |
Avery; Gilbert H. (Memphis,
TN) |
Family
ID: |
22225852 |
Appl.
No.: |
05/091,072 |
Filed: |
November 19, 1970 |
Current U.S.
Class: |
165/215; 236/13;
165/103; 454/267 |
Current CPC
Class: |
F24F
3/0442 (20130101) |
Current International
Class: |
F24F
3/044 (20060101); F24f 003/06 () |
Field of
Search: |
;165/22,30,35,36,37,103
;236/13 ;98/38 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Davis, Jr.; Albert W.
Claims
I claim:
1. A variable volume constant throw terminal re-heat system for
temperature conditioning the air of a room in a building comprising
an air supply source, grille means opening into said room, duct
means for communicating said air supply with said grille means, a
unit including a housing defining a passage for air to flow
therethrough, said housing being interposed in said duct means,
means for heating said air supply, said heating means being
positioned internally of said housing, heating damper valve means
having infinite positions for selectively and gradually admitting a
portion of said air supply linearly through said heating means and
for selectively stopping the passage of said air supply through
said heating means; cooling damper valve means having at least an
open position, intermediate positions and a closed position for
thermal sealing the downstream side of said heating means when in
said open position, for selectively reducing the cross sectional
area effectively of said passage when in said intermediate
positions, and for selectively stopping the passage of air to said
grille means, except the air which may be admitted through said
heating means, when in said closed position; and means for
proportionally varying the volume of air passing through said
housing to maintain a constant air pressure adjacent to and
upstream of said heating and cooling damper valve means
irrespective of the positions thereof.
2. The apparatus of claim 1 which includes means dividing said
passage into an upper flow path and a flower flow path containing
said heating means, with said lower flow path being disposed below
said upper flow path to cause the heated air to exit from said
grille below the cooler air.
3. A variable volume constant throw terminal re-heat system for
temperature conditioning the air of a room in a building comprising
a cooled pressurized air supply source, grille means opening into
said room, duct means for communicating said pressurized air supply
source with said grille means, a unit including a housing defining
a passage for air to flow therethrough, said housing being
interposed in said duct means, means for heating said air supply,
said heating means being positioned internally of said housing
downstream from said pressurized air source, heating damper valve
means having infinite positions including an open position and a
closed position for selectively and gradually admitting a portion
of said air supply linearly through said heating means as said
heating damper valve means is moved from said closed position to
said open position and for selectively stopping the passage of said
air supply through said heating means when moved to positions
including at least an open position, intermediate positions and a
closed position for thermal sealing the downstream side of said
heating means when in said open position to insulate said heating
means from said air supply as it passes adjacent thereto, for
selectively reducing the cross sectional area effectively of said
passage when in said intermediate positions, and for selectively
stopping the passage of air to said grille means, except the air
which may be admitted through said heating means, when in said
closed position; control means including thermostatic switch means
positioned in said room operably coupled to said cooling damper
valve means for actuating said cooling damper valve means, means
interconnecting said heating damper valve means with said cooling
damper valve means for sequentially actuating said heating damper
valve means with said cooling damper valve means as said cooling
damper valve means responds to said thermostatic switch means, and
means for maintaining a constant air pressure within said housing
as said heating and cooling damper valve means sequentially respond
to said thermostatic means.
4. The apparatus of claim 3 in which said means interconnecting
said heating damper valve means and said cooling damper valve means
is arranged so that said heating damper valve means remains in said
closed position as said cooling damper valve means moves between
said open position and a predetermined one of said intermediate
positions and said heating damper valve means being also arranged
to move from said closed position to said open position as said
cooling damper valve means moves from said one of said intermediate
positions to said closed position, said movement of said heater
damper valve means being proportionate with said movement of said
cooling damper valve means.
5. The apparatus of claim 4 in which said heating means, said
heating and said cooling damper valve means are located terminally
of said duct means adjacent said grille means and are arranged so
that the total area of said grille means passes air therethrough
when said heating damper valve means is in said closed position and
said cooling damper means is in said open position.
6. The apparatus of claim 3 in which is included air return duct
means having an opening at the one end thereof leading into said
room, said opening communicating with said cooled pressurized air
supply source for receiving a volume of ambient air from said room
and thereby returning it to said air supply source, and said means
for maintaining a constant air pressure within said duct means
includes by-pass damper valve means adjacent said cooling damper
valve means for by-passing a variable volume, having predetermined
limits, of cooled air from said housing and being operable
responsive to actuation of said cooling damper valve means.
7. The apparatus of claim 6 in which said by-pass damper valve
means includes by-pass duct means communicating with said air
return duct means for recirculating said variable volume of cooled
by-passed air through said pressurized air supply source.
8. The apparatus of claim 6 in which is included means for holding
said heating damper valve means in said closed position while said
cooling damper valve means and said coacting by-pass damper valve
means continue to be operably responsive to said thermostatic
switch means.
9. The apparatus of claim 5 in which is included baffle means
adjacent said grille means for maintaining optimum air velocity
through said grille means as said cooling damper valve means is in
the range between said predetermined intermediate position and said
closed position and said heating damper valve means is in the range
between said closed position and said open position.
10. The apparatus of claim 9 in which said baffle means has at
least an operable position and a non-operable position, and in
which is included spring means for urging said baffle means from
said non-operable to said operable position, and means for holding
said baffle means in a predetermined position defining said
operable position.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to forced air temperature conditioning
systems having ducts for circulating the conditioned air to the
various rooms or zones in a building. More specifically, the
invention relates to apparatus for controlling and distributing the
conditioned air supplied to each room or zone of the building.
2. Description of the Prior Art
In a conventional re-heat system all the supply air is cooled low
enough so that any zone or space can be conditioned when that zone
re-heat system is off. The other zones that are calling for less
than maximum cooling are maintained at a satisfactory temperature
by re-heating the supply air with conventional heat transfer
equipment such as a hot water coil. This type system is expensive
to operate in that all the air must be cooled to design conditions
and then re-heated to satisfy the room thermostat.
An improvement over a straight re-heat system is disclosed in my
U.S. Pat. No. 3,433,295 which provides the following advantages
over a straight re-heat system:
A. When the space is calling for heat, only part of the supply air
is heated and the rest of the air is by-passed back to the air
handling unit. Inasmuch as the air that is by-passed is already
cooled, it reduces the load on the air-handling unit.
B. The damper arrangement that controls the heating coil is
superior to the straight re-heat system in that the heat delivered
by the heating coil is proportional to the damper position. This is
not true when the heat output is controlled by a valve throttling
the water flow to a coil. Also, there is less maintenance since
there is no valve on the heating coil to cause trouble.
C. The air velocity out of the supply grille remains relatively
constant throughout the cycle. This maintains proper air
circulation in the conditioned space.
There are, however, distinct disadvantages in practicing my U.S.
Pat. No. 3,433,295 patent:
A. It is necessary to size the grille so that it may handle the
cooled air through one portion thereof and the heated air through a
separate portion thereof, e.g., if the design engineer determined
that it is necessary to move 100 cubic feet per minute, to be
necessary for heating, the grille would have to be sized so as to
move 150 cubic feet per minute, because only part of the grille is
used for cool air and a separate part is used for heated air.
b. The downstream side or back side of the heat coil is not thermal
sealed from the moving air stream which results in heat pickup from
the heat coil as the colder air passes adjacent thereto when the
thermostat is demanding full cold air. Obviously, this reduces the
efficiency of the system since the heat pickup from the coils
reduces the transfer of B.t.u.'s from the room. Additionally, the
heat loss adds to the operational cost of the system since the
coils are automatically maintained at a predetermined temperature,
i.e., when the temperature drops in the heat coils, the boiler
automatically is fired up to return the temperature therein back to
a predetermined level.
c. When the temperature of the ambient air adjacent the thermostat
is cooler than the setting thereof, the system immediately directs
some of the cool air through the heat coils. This, too, does not
lend itself to an economical operation because heat energy is used
when it may not have been necessary.
SUMMARY OF THE INVENTION
The present invention is directed towards overcoming the
disadvantages and problems relative to previous air conditioning
systems. The apparatus of the present invention generally includes
a duct for carrying air from the air supply source to the room, a
unit interposed in the duct, heat coils or the like positioned
internally of the unit, preferably adjacent the grille leading into
the room, a heating damper for gradually admitting a portion of air
linearly through the heating coils and for selectively stopping the
passage of air through the heating coils, a cooling damper, and
structure for proportionally varying the volume of air passing
through the grille or into the room.
When the system is calling for full cooling, the heating coil is
completely isolated from the cold supply air by the heating damper
on the inlet side of the heating coil and by the cooling damper on
the leaving side of the heating coil.
By sequencing the heating damper with the cooling damper, no heat
is supplied to the room until the cooling damper reaches a
predetermined position, as selected by the design engineer, i.e.,
the heating damper remains closed while the thermostat actuates the
cooling damper to control the volume of cool air entering into the
room. The velocity of the air entering into the room is maintained
constant by the structure for proportionally varying the volume of
air passing through the grille, e.g., a by-pass damper or the like.
In other words, one such system might be designed so that half of
the air is being delivered to the room and the other half is
by-passed back to the air supply source, the cooling damper and
by-pass damper operably responding to a pneumatic thermostat or the
like. However when this arrangement does not satisfy the setting on
the thermostat, the heating damper, also operating responding to
the thermostat, gradually opens so as to admit a portion of the
cool air over the heat coils. The confluence of the heated air and
the cool air adjacent the grille opening into the room causes the
temperature therein to rise gradually so as to meet the demands of
the thermostat.
The apparatus of the present invention utilizes the whole face of
the supply grille when the system is calling for full cooling,
i.e., the area of the supply grille can be reduced considerably
over the prior systems, e.g., 66 percent, when using the
specifications described earlier.
A further advantage of the system of the present invention is
directed towards certain air conditioning systems where there is no
heating medium available certain times of the year, e.g., most
schools shut off their boilers in the summertime. When this
happens, with conventional re-heat systems, the space is
overcooled. However, the control system of the present invention
provides structure so that is there is no heat media available, the
heating damper can remain closed during these periods. Since the
cooling damper in response to the thermostat will go closed, as the
space temperature drops, the likelihood of overcooling the
conditioned room will no longer be a problem.
During the winter months when the thermostat is calling for full
heat, the cooling damper automatically remains closed, and the
heating damper operably responds to the thermostatic demands so as
to move sufficient heated air through a portion of the grille with
the same velocity as when the entire grille face was used.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational sectional view of the variable volume
constant throw terminal re-heat unit, showing the various dampers
positioned as they would appear for delivering maximum cooling.
FIG. 2 is identical to FIG. 1, except that the various dampers are
shown positioned for delivering minimum cooling and no heat.
FIG. 3 is identical to FIGS. 1 and 2 except the various dampers are
shown in full lines positioned for delivering full heating, and in
broken lines in an intermediate position.
FIG. 4 diagrammatically depicts the unit of the present invention,
showing it as it would appear when delivering full cooling in a
typical environment arrangement or system.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The variable volume constant throw terminal re-heat unit or
apparatus of the present invention is herein character referenced
by the numeral 11 and is intended to be a part of a system 12 (FIG.
4) for temperature conditioning the air of a room 13 is in a
building. System 12 generally comprises a conventional cooled and
pressurized air supply source 15, a grille 17 opening into the room
13, a duct 19, heating coils 21, a heating damper valve 23, a
cooling damper valve 25, and structure for proportionally varying
the volume of air passing through the grille 17, e.g., a by-pass
damper valve 27 or the like. It should be pointed out that the
bypass valve 27 (FIG. 4) leads into a duct 29 communicating with
the air supply source 15. However, an air return duct 31 having an
opening at the one end thereof leading into the room 13
communicates with the air supply source in a typical manner so as
to receive a volume of ambient air from the room 13 and return it
to the air supply source. Accordingly, the air return duct 29, as
depicted in FIG. 4, preferably would connect to the air return duct
31 at a convenient location along the length thereof, i.e.,
obviating the necessity of providing an independent duct system for
returning the by-passed air.
It should be pointed out that the apparatus 11, as herein
described, is conveniently directed towards servicing a single room
13. However, in actual practice the apparatus 11 would more than
likely be most beneficial in a large building, e.g., a hotel or
school or the like, having numerous rooms with each room having a
unit 11 connected in to a master pressurized air supply source.
Additionally, in the course of describing the apparatus 11, various
values of air pressure will herein be referred to, e.g., 71/2 lb.
per square inch or 15 lb. per square inch. However, these values
are intended to be representative values and are conveniently used
to described the structure apertaining thereto. In other words,
these values are given by way of illustration and not
limitation.
The system 12 includes a temperature responsive device, e.g., a
pneumatic room thermostat 33 which causes pressure to vary linearly
with a change in temperature. The pressure output of the thermostat
has the usual operating range, e.g., 0 to 15 lb. per square inch.
The thermostat 33 preferably is connected to a constant air
pressure source, e.g., a motor-driven air pump 35 or the like. by a
conduit or flexible tubing 37.
The unit 11 of the present invention is depicted in the drawings as
being interposed in duct 19 immediately adjacent the grille 17
which opens into the room 13, with a short portion 19' of duct 19
being between grille 17 and unit 11. However, it should be
understood that the unit 11 may be used with an indefinite length
of supply duct interposed between the unit 11 and the grille 17
without departing from the spirit and scope of the present
invention.
The unit 11 is provided with a boxlike or sleevelike housing 39,
which is open at the opposite ends thereof and defines a passage 42
for air to flow therethrough. Housing 39 has structure obvious to
those skilled in the art adapted to be fitted at the one end to the
duct 19 and at the other end to the duct 19'. A fixed baffle plate
40 extends transversely across the interior of housing 39 as
depicted in the drawing to divide the passage 42 generally into an
upper flow path 39' and a lower flow path 39". The heating,
cooling, and by-pass damper valve 23, 25, 27, preferably being
formed from sheet steel or the like, have a leaf or blade-type
typical construction, i.e., they have the usual structure for
pivotal attachment to the housing 39, obvious to those skilled in
the art.
Referring now to FIG. 1 of the drawings wherein the preferred
positioning of the valves 23, 25, 27 is depicted when the
thermostat 33 is demanding full cooling, when the unit 11 is
delivering full cooling, the heating damper valve 23 is closed so
as to deflect the air, diagrammatically depicted by a plurality of
arrows, upwardly away from the heating coils 21. Additionally, the
cooling damper valve 25 is in the open position so that the entire
face of the grille 17 is utilized to deliver this maximum volume of
air into the room 13. Further, the by-pass damper 27 is in a closed
position so that the maximum volume of air is permitted to move on
through the unit 11.
It should be pointed out that the valves 23, 25, 27, as herein
disclosed, are controlled by individual pneumatic actuators, yet to
be disclosed, and the sequencing of the system is accomplished by
selecting an actuator having the proper spring range to accomplish
the desired function. However, this same sequence may be
accomplished by using a single actuator having suitable mechanical
linkage attached thereto without departing from the spirit and
scope of the invention, i.e., the structure for the aforementioned
single actuator having mechanical linkage to sequentially perform
the intended functions herein is obvious to those skilled in the
art. In this regard, a pneumatic actuator 41, being operably
responsive linearly between 0 and 71/2 lb. per square inch, having
an actuator arm 43, is mechanically connected to the heating valve
23 in any well known manner, e.g., a mechanical linkage member 45.
The one end of the member 45 is fixedly attached to the valve 23 in
any well known manner, e.g., welding or the like, so that when the
actuator 41 drives the actuator arm 43, the linkage member 45 moves
the valve 23 from a closed position (FIG. 1) to an open position
(FIG. 3), in a manner well known to those skilled in the art.
The actuator 41 is in communication with the thermostat 33
pneumatically through a conduit 47 (FIG. 4) extending from the
actuator 41 to a valve 49, thence through the valve 49 to a conduit
51 (having junctions therein leading to structure yet to be
disclosed) thence to the thermostat 33. In other words, the valve
23 is operably responsive to the thermostat 33, i.e., when the
pneumatic pressure in the conduit 47, 51 drops below 71/2 lb. per
square inch, the damper valve 23 is caused to move proportionally
from a closed position toward an open position as the pneumatic
pressure drops.
Additionally, a pneumatic actuator 53, being operably responsive to
pneumatic pressures in the range between zero to 15 lb. per square
inch, includes an actuator arm 55 which linearly moves to and fro
in response to the amount of pressure which the thermostat 33 is
putting out, i.e., a conduit 57 connects the actuator 53 with the
previously described conduit 51. In other words, the damper valve
25 maintains an open position (FIG. 1) when the pneumatic pressure
in the conduits 51, 57 is 15 lb. per square inch and as the
pneumatic pressure in the conduits 51, 57 gradually diminishes to
71/2 lb. per square inch, the damper valve 25 gradually moves to an
intermediate position, substantially as depicted in FIG. 2, and as
the pressure in the conduit 51, 57 gradually diminishes to 0 lb.
per square inch, the damper valve 25 gradually moves to the closed
position shown in solid lines in FIG. 3. Obviously, the actuator
arm 55 and the damper valve 25 are interconnected with suitable
mechanical linkage, e.g., members 59, 61. The member 61 has the one
end thereof fixedly attached to the damper 25 in any well known
manner, e.g., welding or the like, and the other end thereof is
pivotally attached to the one end of the member 59 and the other
end of the member 59 is pivotally attached to the actuator arm 55,
which includes structure well known to those skilled in the
art.
Further, a pneumatic actuator 63, being operably responsive to a
range of pneumatic pressures between 71/2 and 15 lbs. per square
inch communicates with the thermostat 33 through the aforementioned
conduit 51 and a junction thereto including a conduit 65. The
actuator 63 includes an actuator arm 67 mechanically connected to
the damper valve 27 through a pair of mechanical linkage members
69, 71, i.e., the one end of the member 71 is fixedly attached to
the damper valve 27 in any well known manner, e.g., welding or the
like, and the other end thereof is pivotally attached to the one
end of the member 69, the other end of the member 69 is pivotally
attached to the actuator arm 67, which includes structure well
known to those skilled in the art. In other words, when the
pressure in the conduits 51, 65 is 15 lb. per square inch, the
damper valve 27 is in the closed position (FIG. 1) and as the
pressure in the conduits 51, 65 gradually diminishes to 71/2 lb.
per square inch, the actuator 63 causes the damper valve 27 to
gradually move to the open position (FIGS. 2 and 3). It should be
noted that the damper valve 25 seals the heating coil 21 against
heat loss as the cooler air moves adjacent thereto en route to the
grille 17, i.e., when the damper valve 25 is in the open position
(FIG. 1).
Referring now to FIG. 2 of the drawings wherein it may be seen that
the cooling valve 25 has moved to an intermediate position and the
by-pass valve 27 has moved to the open position so that
approximately 50 percent of the total volume of air is by-passed to
the air supply source and the remaining 50 percent moves on through
the unit 11 and is discharged therefrom through the grille 17. In
other words, as the thermostat 33 calls for less cooling, the
cooling damper 25 moves up across the face of the grille 17 so as
to close off the discharge opening and at the same time the
by-passed damper 27 starts to open and pass the excess air back to
the air supply source 15. The complementary action of the dampers
25, 27 maintain a constant velocity of air flow from the grille 17
as the volume emitting therefrom varies. It should be understood
that the above disclosure, being based on by-passing 50 percent of
the air back to the air supply source when the unit 11 is in a
minimum cooling no-heat condition (FIG. 2) is given by way of
illustration in explaining the operation of the device and is not
to be so limited since other values may be used without departing
from the spirit and scope of the present invention.
An important feature of the unit 11 of the present invention is
sequencing the heating damper 23 with the cooling damper 25 so that
the temperature in the room 13 can be gradually reduced without
consuming heat energy, i.e., heat is not used until the cooling
damper 25 reaches a predetermined position as selected by the
design engineer. FIG. 2 of the drawings shows the dampers 23, 25,
27 in an optimum position for the unit 11 to deliver minimum
cooling. It should be observed that the heating damper 23 is still
closed and that the cooling damper is at an intermediate position,
the by-pass damper 27 is wide open, and that half of the air
(arrows) is being delivered to the room 13 and half is by-passing
back to the air supply source 15. When the valves 23, 25, 27 are
positioned as depicted in FIG. 2 of the drawings, the output of the
thermostat 33 preferably would be at its mid-range, e.g., 71/2 lb.
In other words, the output from the thermostat 33 has dropped from
15 lb. for the condition depicted in FIG. 1 of the drawing to 71/2
lb., i.e., the pressure in the interconnected conduit 47, 51, 57,
65 has not reached the operable range for the actuator 41 so the
valve 23 remains closed, the pressure has reached the lower limit
for the actuator 63 so that the valve 27 is fully open, and the
pressure has reached a mid-point in the operable range for the
actuator 53 so that the valve 25 is in an intermediate
position.
The unit 11 of the present invention is depicted in a full heating
condition in solid lines n in FIG. 3 of the drawings. The unit 11
includes a baffle assembly 73 for maintaining optimum air velocity
through the grille 27 as the cooling damper 25 moves into the range
of positions between a predetermined intermediate position and the
closed position and the heating damper 23 is in the range between
the closed position and the open position It should be understood
that the baffle assembly 73 is optional and particularly would not
be recommended when the output from the unit 11 empties into a
length of supply duct rather than into an adjacent grille 17.
It will be noted that there are positions of valves 23, 25
illustrated in FIG. 3 in broken lines as at 23', 25' which are
intermediate positions between that shown in solid lines in FIGS. 2
and 3 in which positions 23', 25' the thermostat 33 is calling for
some heating. In this example shown in broken lines, the thermostat
is calling for one-half heating and the air pressure is 33/4 lb. It
might appear that the low velocity heated air moving through lower
flow path 39" would not carry or produce the blow that the higher
velocity cold air that is moving through upper flow path 39' and
coming out of the top of the unit would produce. However, this is
not the case since induction and convection will rapidly mix the
warm air with the cold air stream to provide essentially the same
throw. The streams will mix by induction since the slow moving warm
air will be induced by the higher velocity cold air and the warm
air will rise by convection into the cold air stream. With this
operation, the velocity of the air out of the bottom of the unit
(i.e., that moving through lower flow path 39") has little to do
with the total throw out of the box. When the heating damper 23 is
in the full heat position and cooling damper 25 is closed, there is
still essentially the same throw since now there is all of the air
discharging out of the bottom of the unit at the desired velocity
to produce the proper throw out of the unit.
Baffle assembly 73 includes not only fixed baffle plate 40,
heretofore mentioned, but also a movable baffle plate 77 which
extends from side to side of the housing 39 and is pivotally
attached to fixed baffle plate 40 in a manner obvious to those
skilled in the art. The plate 77 has at least an operable position
(FIG. 3) and a non-operable position (FIG. 1) and is spring biased
to the operable position by a spring 79 in a manner obvious to
those skilled in the art. The baffle assembly 73 also includes a
flexible length of chain 81 for holding the movable baffle plate 77
in a predetermined operable position, i.e., the chain 81 has one
end thereof fixedly attached to the plate 77 and the other end
thereof fixedly attached to the housing 39 in a manner obvious to
those skilled in the art.
It should be understood that when the unit 11 is delivering full
heat (solid line position of FIG. 3), the output air pressure from
the thermostat 33 would be nil, i.e., diminished to 0 lb. per
square inch. Obviously, the actuator 63 has not changed from the
position depicted in FIG. 2 since the pressure, 71/2 lb. per square
inch, was at the lower limit, accordingly, lowering of the pressure
to 0 lb. per square inch in the system has no further effect upon
the position of the damper 27. However, the zero pressure in the
system causes the actuator 41 to move to its opposite limit so that
the heating damper 23 is fully open and the actuator 53 is moved to
its opposite limit so as to cause the cooling damper 25 to move to
the fully closed position. In other words, using the values
conveniently referenced above, the unit 11 is by-passing 50 percent
of the supply air back to the air supply source 15 and re-heating
the remaining 50 percent of the air, when the thermostat 33 is
calling for full heat. It should be understood that this ratio is a
variable and is normally selected by the design engineer. For
example, in some instances it may be desirable to by-pass
two-thirds of the air back to the air supply source and move only
one-third of the air through the heating coil 21 when the unit 11
is in the full heat output condition.
It should be understood that the above disclosure depended upon
having the dampers 23, 25, 27 positioned at their limits when in
actuality the air pressure output of the thermostat 33 is a gradual
changing pressure and the conduits 47, 51, 57, 65 interconnect the
actuators 41, 53, 63 so that this gradual pressure change slowly
moves the appropriate dampers 23, 25, 27 through infinite
intermediate positions so that a smooth transition of air
displacement takes place, i.e., the valves 25, 27 do not abruptly
move from the position depicted in FIG. 1 to the position depicted
in FIG. 2, nor do the valves 23, 25 abruptly move from the position
depicted in FIG. 2 to the broken line positions and then to the
solid line positions depicted in FIG. 3. In other words, after the
unit 11 passes through the 50 percent by-pass and 50 percent
delivered to the grille 17 and the thermostat 33 calls for more
heating, the heating damper 23 starts to open and the cooling
damper 25 continues to move across the face of the grille 17 until
the cool air is completely stopped. At this time, the heating
damper 23 has fully opened so that the volume of air moving through
the grille 17 must first travel through the heat coils 21. Further,
the velocity of the air is maintained constant by the baffle plate
77 to effectively reduce the cross sectional area of the housing
39.
In some air conditioning systems, there is no heating medium
available at certain times of the year, e.g., most schools shut off
their boilers in the summertime. When this happens, with
conventional re-heat systems, the room 13 would probably overcool.
A feature of the present invention obviates this problem by
incorporating a pair of valves 49, 83. The position of the valve 49
(FIG. 4) in the system 12 was previously disclosed. The valve 83
has the one end thereof communicating with the air pump 35 and the
other end thereof communicating with the conduit 47 leading into
the actuator 41. When the heating medium or, in this case, the
coils 21 is/are operating the valve 49 is fully open, and the valve
83 is fully closed so that the output pressure from the thermostat
33 is delivered through the valve 49 to the actuator 41 and the
output from the pump 35 is delivered only through the conduit 37 as
previously described.
However, when the heating medium or the boilers (not shown) which
deliver the heat to the coils 21 is/are shut down so that the coils
21 are not heated, the valve 49 is completely closed, and the valve
83 is fully opened so that the actuator 41 is isolated from the
output pressures of the thermostat 33. In other words, the object
is to keep the heating damper 23 in the fully closed position as
shown in FIG. 1 and 2. Accordingly, the 15 lb. pressure from the
air pump 35 is constantly applied to the actuator 41 which causes
the heating damper 23 to remain closed, the pressure being over the
required 71/2 lb. per square inch, as previously disclosed. In this
arrangement, the cooling damper 25 and the by-pass damper 27 are
still interconnected and function in the same manner as previously
described, i.e., operably responding to the thermostat 33. In other
words, since the cooling damper 25 will go closed, as the
temperature in the room 13 drops, overcooling the room 13 will no
longer be a problem.
It should be understood that the by-pass damper 27 is optional,
i.e., the damper valve 27 being just an example of how the pressure
in the supply air system could be maintained constant. This could
be accomplished in any of the well known techniques, e.g.,
providing a damper adjacent the blower, i.e., a component part of
the pressurized air supply source 15, and this damper could be
opened and closed in like manner as the previously described
by-pass damper 27 operably responds to the thermostat 33.
Obviously, during the winter months the refrigeration system (not
shown), which is a part of the cooled pressurized air supply source
15, would preferably be shut down so that the air supply introduced
to the unit 11 through the duct 19 would be ambient air or cooler
air returned from the room 13, in a manner obvious to those skilled
in the art. An object of the unit 11 is that all of the air in the
room 13 is constantly being changed in the winter and the summer so
as to remove smoke and/or other objectionable odors and to maintain
a fresh air environment therein. This is accomplished principally
by varying the volume of air moving into the room 13 in a unique
manner of maintaining a constant velocity thereto so that the air
always moves a predetermined distance into the room away from the
grille 17 and gradually settles down so that no cold blasts of air
are felt by the people who might be in the room 13.
Although the invention has been described and illustrated with
respect to a preferred embodiment thereof, it is not to be so
limited since changes and modifications may be made therein which
are within the full intended scope of this invention.
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