Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a motorized damper
for a forced air system, typically a forced system of
the kind found in homes.
Homes having warm air heating systems normally
have warm air ducts which lead to the various rooms
in the home, and dampers which are located at the ends
of the ducts to control the flow of warm air in the
room. The dampers presently used are manually operated,
usually by a thumbwheel or other control located in
the damper. A manual control is usually stiff and
difficult to operate and additionally is located at
floor level where it is difficult to reach. In some
cases the damper may be located beneath or behind
furniture, where it is impossible to reach. For these
reasons, the manually operated dampers found in homes
are rarely if ever operated, and warm air is allowed
to flow into each room in the home regardless of
whether the room is occupied.
The failure to use manually operated dampers
in homes results in a substantial wastage of fuel. If
rooms which are not in use were allowed to remain
unheated, except for heat flowing from the remainer of
the home, then such rooms would typically assume a
temperature of 10 to 15~F less than the remainder of
the home which is heated. If substantial portions
of the home were allowed to remain unheated while they
were not in use, then very large savings in fuel could
be achieved.
Accordingly, the present invention provides a motor-
ized damper which is extremely simple but unique in design,
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inexpensive to construct, and which can be operatedin a very simple manner to shut off the flow of warm
air to a room or to admit warm air to the room, as
desired. In one embodiment the invention provides a
forced air damper comprising a housing having a passage
for flow of air therethrough, a damper plate, and
axle means in the housing mounting the damper plate in the
passage for continuous rotation in one direction through
360~, so that the damper plate in one position will close
the housing to flow of air therethrough and in a second
position rotated through an angle from a first position
will open the housing to flow of air therethrough. An
electric motor is connected to the axle means for
rotating the damper plate in the required direction when
the motor is energized, and two-way switch means are
provided having three contacts, one contact connected to
the motor and two contacts adapted to be connected to a
second two-way switch. The two-way switch means
includes actuator means operable for connecting the motor
lead alternately sequentially to one and then the other of
the switch contacts, so that the switch has a first switching
~ condition when the motor lead is connected to one contact
- and a second switching condition when the motor lead is
connected to the second switch contact. The contacts
of the switch means are mounted on the housing and the
actuator means is mounted on the damper plate. The switch
means and damper plate are located so that rotation of the
damper plate from its first to its second position will
operate the actuator means to place the switch means in
one switch condition and for rotation of the damper plate
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from its second to its first position to operate the
actuator means to place the switch in its second switch
condition~ By this arrangement a second two-way switch,
which may be located at the entrance to a room in which
the damper is located, can be operated when the occupier
enters the room, to cause the damper plate to rotate to its
open position. When the damper plate reaches its open
.
position the electric motor will shut off, due to the two-
way switch means on the damper, and heat will then enter
the room. When the occupant leaves the room, he may
operate the same switch at the door again (since it is
connected in a two-way switch arrangement with the switch
means on the damper), and the damper plate will then
rotate again until it is closed, at which time the two-
way switch means on the damper will again shut off the
electric motor.
If desired, the room switch may be a thermo-
stat, so that control of the heat in the room is automatic,
simply by setting the thermostat.
Alternatively, or in addition, a central processing
unit may be provided to operate allo f the dampers according
to a predetermined program, and an override switch may be
provided so that when an occupant enters a room and operates
a switch to open its damper, he may also operate the over-
ride switch to close the dampers in all of the other rooms
in the house for a predetermined interval, for example
five minutes. During this time all of the warm air output
from the furnace will be forced into the room which the
occupant has entered, thereby rapidly heating that room
to the desired temperature. The other rooms will cool
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only slightly during this relatively short interval.
After the predetermined time interval has elapsed, the
system resumes its normal condition.
Further objects and advantages of the invention
will appear from the following description, taken together
with the accompanying drawings, in which:
Fig. 1 is a perspective view, partly cut away,
showing a damper according to the invention;
Fig. 2 is a top plan view of the damper of
Fig. l;
Fig. 3 is an end view of the damper plate of
the Fig. 1 damper;
Fig. 4 is a schematic of a circuit for the
damper of Fig. l;
Fig. 5 is a diagrammatic view of a room in
which a damper according to the invention is installed;
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Fig. 6 is a schematic of a slightly modified
circuit for the damper of Fig. l;
Fig. 7 is a perspective view of a portion of
the damper of Fig. 1 and showing ratchet means in
position to prevent reversal of the direction of movement
of the damper plate;
Fig. 8 is a perspective view showing a modified
device for preventing reversal of the damper plate
direction of rotation;
Fig. 9 is a perspective view showing a modified
switch for the damper of Fig. l;
Fig. 10 is a perspective view showing a further
modified switch for the damper of Fig. l; and
Fig. 11 is a schematic view of a central
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processor arranged to control a multitude of dampers
according to the invention, and with an override
switch for each damper.
Reference is first made to Fig. 1, which shows
a damper generally indicated at 10. The damper 10
includes a housing 12 having two elongated sides 14, 16
and two ends 18, 20 which are arranged to form a
rectangular box having a through opening 22 therein. --
Mounted in the opening 22 is a rectangular damper
plate 24.
The damper plate 24 carries a pair of stub
axles 25, 26, one at each end thereof. The axle 25
is journalled in a hole (not shown) in a channel-shaped
piece of sheet metal 28 welded to the end plate 18. The
- axle 26 extends through a hole in the end plate 20 and
is connected to an electric motor 30 (Fig. 2).
The electric motor 30 (which includes built-in gears,
.~ not shown, to provide an appropriate low output speed)
is arranged to rotate the damper plate 24 in the direction
of arrow A, Fig. 1.
As will be apparent from the drawings, the
damper plate 24 substantially closes the opening 22
when it is in a horizontal position, and presents a
minimum obstruction to air flow when it is in a vertical
position (in which case the damper is termed "open").
Two-way switch means are provided to control
the operation of motor 30 in conjunction with a second
two-way switch mounted near the room entrance, so that
the damper plate can be stopped simply and automatically
in either its closed or its open positions. The two-
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way switch means of the damper includes a single pole
double throw microswitch 32 having a pair of fixed
contacts 34, 36 (Figs. 2 and 4) and a movable contact
38. The movable contact 38 is operable by a lever arm
40 which is hinged at one end to the microswitch and which
extends outwardly horizontally into the path of the
damper plate 24. Whenever the lever arm 40 is pushed
toward the microswitch body, it operates a conventional
plunger 41 (which is spring biased outwardly by a spring
not shown) to move the contact 38 alternately sequen-
tially from contact 34 to contact 36 and then back
again, as is conventional for a single pole double throw
microswitch.
The switch means of the damper also includes
a pair of actuator plates 42, 44 mounted at the end of
the damper plate 24 adjacent the microswitch 32. The
actuator plates 42, 44 are located in a common vertical
; plane, one at each side of the damper plate 24, and each
spaced slightly sideways of the axle 26. Each actuator
plate 42, 44 has generally the form of a quarter circle
and each extends in an opposite direction from the other
so that when the damper plate 24 for example is horizontal,
actuator plate 42 extends upwardly and actuator plate 44
extends downwardly. Each actuator plate has an outer
periphery 46 of circular configuration, and an inner edge
48 which extends at right angles from the damper plate 24
to meet the outer periphery 46.
As shown in Figs. 4 and 6, the contacts 34,
36 of the damper are connected to contacts 50, 52 of
another two-way switch 54 having a movable contact 56.
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Contact 56 is connected to one side of a power source 58
(typically 110 volts), the other side of the power source
being connected through lead 60 to one side of the motor 30.
The other side of the motor 30 is connected to movable
contact 38. Switch 54 is typically located beside the
door 62 (Fig. 5) of a room 64 in which the damper 10
is located.
The operation of the damper 10 is as follows.
Assume that the damper plate 24 is in a horizontal
position, in which case the damper is closed. In this
condition neither actuator plate 44 nor actuator plate
42 is contacting the lever arm 40 and the condition of
the two-way switch means of the damper will be as shown in
Fig. 4. In this condition no complete circuit is made
from power source 58 through the two two-way switches
to motor 30 and the motor remains off.
When an occupant enters the room, he operates
two-way switch 54 to move the contact 56 to connect to
contact 50. This energizes the motor 30 and the damper
~ 20 rotates in the direction of arrow A. As the damper
- rotates, the edge 66 of actuator plate 44 moves against
and depresses the lever arm 40, depressing the plunger -
41 of the microswitch 32 and thereby moving the contact
~; 38 to connect to contact 36. This opens the motor circuit
and the motor 30 stops with the damper plate 24 in its full
open position. The actuator plate 44 holds the lever
arm 40 depressed even after the edge 66 passes the end
of the lever arm 40.
When the occupant leaves the room 64, he
again operates the switch 54, moving contact 56 to
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connect to contact 52. This re-energizes the motor
30 and the motor operates, turning the damper plate 24
until the damper plate has reached its horizontal
position. At this time the edge 48 of actuator plate
44 moves off the lever arm 40, allowing the plunger 41
to move outwardly under the spring bias of the micro-
switches 32 . This moves movable contact 38 back to
contact 34, opening the motor circuit and stopping the
~ motor 30 with the damper in its closed posltion.
-~ 10 When the process is repeated by an occupant
re-entering the room and reoperating switch 54, and
causing the damper plate to rotate again, actuator
plate 42 will operate the lever arm 40, operating the
microswitch 32 to open the motor circuit to hold the
damper plate in open position. Then, when the occupant
leaves the room and reoperates the switch 54, the motor
30 rotates the damper plate 24 towards its closed
posiiion, at which time actuator plate 42 will release
the lever arm 40 to stop the motor with the damper
20 plate 24 in its closed position. -
; In summary, it will be seen that the damper
10 has two closed positions and two open positions,
each open position being located between a pair of ~ -
closed positions, and the various positions being reached
` by continuous rotation of the damper plate 24 in one
direction only. The damper includes two-way switch means
connected to a two-way switch in the room in which the
; damper is located, so that whenever the room two-way
switch 54 is operated, the damper will change its
position, either from open to closed or from closed
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to open. Because the rotation is continuous in one
direction, the damper 10 may be made simply and inexpen-
sively and without high precision being required. If
desired, only one actuator plate 42 or 44 could be
provided, but two are preferred.
If desired, a thermostatic switch 67 (Fig. 6)
- may be used in place of the two-way switch 54. The
switch 67 is a single pole double throw switch identical
to switch 54, except that it is thermostatically operated
by a conventional temperature sensor 68 which controls a
conventional thermostat actuator 69. Whenever the
temperature sensor senses a change in temperature past
its high or low settin~, it operates actuator 69 which
operates in the same manner as microswitch plunger 41.
Actuator 69 then moves contact 56' to change its connection,
either from contact 50' to contact 52' or vice versa. The
switches 67 and 32 are initially set so that when the
temperature sensor moves past its high limit, the damper
will move from its open to its closed position. The
thermostatic switch 67 may be located near the door of
a room in the same position as switch 54 so that it can
readily be set by an occupant.
When a very inexpensive electric motor 30 is used,
for example a shaded pole motor, the motor 30 may sometimes
have a tendency to rotate slightly in a direction reversed
- to that indicated by arrow A, before it resumes its
correct direction of rotation. This is undesirable when
the damper is initially open, since the edge 66 of the
actuator plate 42 maymove off the lever arm 40, shutting off
the unit. Therefore, if desired, ratchet means indicated in
Fig. 7 may be provided to ensure that the damper plate 24
can rotate for example from its open position only in one
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direction. The ratchet means of Fig. 7 consists of two
metal strips 70, 72 secured to a side flange 74 at the top
of the damper 10 and extending horizontally outwardly towards
the damper plate 24. The metal strip 70 lies in a vertical
plane and has a sloping end 76 which engages the top of the
damper plate 24 when the damper is in a vertical position, and
prevents the direction of rotation of the damper plate
from being reversed. The metal strip 72 has a series of
saw teeth 78 which engage the upper edge of the damper
plate and add further assurance that the direction of rotation
of the damper plate will not be reversed.
Alternatively, and as shown in Fig. 8, the axle
25 may terminate in a small fine tooth ratchet wheel 80
located between the metal plate 28 and the end wall
18. A short arm 82 secured to plate 28 engages the
teeth of wheel 80 and ensures that the direction of
rotation of the damper plate 24 cannot reverse.
- Reference is next made to Fig. 9, which shows
an alternative switch means for the damper 10. In the ~-
Fig. 9 embodiment, the damper plate 24 is provided
with a circular end plate 84 having a switch contact plate
; 86 mounted thereon. Switch contact plate 86 includes a central
annular contact ring 88, a pair of outer annular contact
segments 90, 92 each extending around an arc of 90 and
each spaced 90 from the other, and a pair of inner
annular contact segments 94, 96 each also extending around
an arc of 90 and spaced 90 from each other. Contact
segment 94 is located between contact segments 90, 92 and
-~ contact segment 96 is located opposite segment 94 and
is also located between segments 90, 92. Contact segments
88, 90, 92, 94 and 96 are all connected to each other
and may be integral. Three brushes 34', 36' and 38'
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are fixed to an insulated mounting piece 98 on the
housing and are connected in the same manner as contacts
34, 36 and 38 of Fig. 4. In operation, as the damper
plate 24 rotates, contact plate 86 will connect either
contacts 34', 38' together or will connect contact
36', 38' together, exactly in the manner of Fig. 4, to
energize or shut off the motor 30 as required. The
brushes 34', 36', 38' will wipe the contact segments
continuously as the damper is used, to keep the contact
segments clean. If desired, the contact plate 86 may be
a transfer or decal which is applied by adhesive to the
; damper end plate 84. Normally the voltage used in the
Fig. 9 embodiment will be a low voltage, for example 12
volts or 24 volts, to avoid dangers of shock to users.
If desired, the arrangement shown in Fig. 10
may be used, in which primed and double primed reference
numerals indicate parts corresponding to those of Fig. 9.
In the Fig. 10 arrangement the contact plate 86' is placed
on the housing 12 instead of on the damper plate 24, and
contact ring 88' is insulated both from contact segments
, 90', 92' and from contact segments 94', 96'. The damper
plate 24' now carries a set of three wiping brushes
99, all connected together and mounted by an insulating
; mounting 100 on the damper plate. The brushes
99 serve to connect central annular ring 88' either
to outer segments 90', 92' or to inner segments
94', 96' as required, again to achieve the desired two
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way switching function. -
It will be appreciated that the damper of the
invention leads itself to central control, so that a
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central processor receiving its inputs from thermostats
in each room and connected to dampers in each room may
control the heat level in each room of a home according
to a predetermined program. Such an arrangement is
shown diagrammatically in Fig. 11, where a central pro-
cessor 101 is shown connected to a set of thermostats
102, 103, 104 and 105, one in each room, and also to
dampers 108, 110, 112 and 114, each associated with a
corresponding thermostat. The central processor, which
may be any conventional processor, such as the many
- mini-computers,(which are programmable) or microprocessors
(which have fixed programs) now commercially available,
may be,arranged to receive the temperature inputs from ,'
thethermostats 102 to 105 and to control the dampers ~ ~-
,~; 108 to 114 to control the room temperatures according
' to a selected program. The output from the processor
to each damper is on three wires, as indicated by wires
' 116, 118, 120 for damper 114. The wires 116, 118
correspond to the wires of Fig. 4 between contacte
~- 20 50, 52 and contacts 34, 36 respectively and wire 120
corresponds to lead 60 of Fig. 4. The processor 100
thus applies power alternatively and sequentially to
wire 116 or wire 118 to reverse the state of damper 114,
exactly as in the Fig. 1 embodiment, i.e. the processor
100 in effect constitutes a number of program controlled
two-way switches.
;~ In addition, as indicated in Fig. 11, each room
;' may also be equipped with an override switch 122, 124, ' ,
126, 128. The override switches are also connected to
the central processor 100. The central processor may be
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programmed so that when an override switch is operated,
the central processor will shut off all the dampers
except the damper for the room in which the override
switch was operated. The shut off will remain
effective for a selected period of time, for example
five minutes, adequate to allow the output of the
furnace to heat more quickly the room in which the
override switch was operated. If desired the central
processor may also be programmed to turn on the
furnace during this period of time, to ensure that an
adequate heat flow into the desired room is available.
Finally, when used with a central processor,
the damper may omit the integral two-way switch and
have instead simply an impulse switch, which sends a
~ pulse to the processor whenever the damper rotates to
- its closed or open position. The impulse switch may be
a microswitch actuated as described (by plates 42, 44) -
or it may be any other conventional switch. When the
processor receives the impulse, it then turns the motor
of the damper off as required. In effect the processor
then constitutes the two two-way switches previously
described.
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