Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND }~ND SUMMARY OF THE INVENTION ~r~ ~
The present invention relates to a system for ~:
automatically lowering the temperature of a room or a house
during certain periods such as the nighttime hours utilizing
the conventional two-conductor wiring ~rom the furnace to
the thermostat control. In this regard, it will be appreciated
that in view of the national need to conserve energy, it is
highly recommended that home temperatures be lowered every
evening. As a practical matter, homc owners will be less . : .
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likely to effect a nightly tempcrature reduction if he must
rcmelnbcr to adjust the thcrmostat each night and must arise
to a cold house cach morning and then readjust the thermostat.
Consequently, the advantages of an automatic system for
reducing the t~mperature setting of the thermostat each night
and fo~r increasing the temperature setting just prior to the
usual awakening time are apparent:.
It will be appreciated that if the installation of
an automatic system requires the trouble and expense of
replacing or supplementing the existing wiring from the
thermostat to the furnace, or the automatic system is costly~
home owners will be discouraged rather than encouraged to
save energy through the installation of an automatic tem-
perature reduction system.
The present invention provides an automatic tem-
perature reduction system for a room or house which is straight-
forward in construction so that it may be manufactured at
low cost, and additionally, utilizes the two existing
conductors of the conventional thermostat wiring. A first
embodiment of the present invention achieves these advantag ~ us
results by providing a temperature control system utilizing
a heat source which is associated with the temperature re-
sponsive element in the heated area and which is activated
during the nighttime hours to make the apparént room tem-
perature appear to be higher than the actual room temperature
thereby causing the temperature responsive element to signal
for a reduction in room temperature. A clock-controlled
adjustable current source for the heater is locat~d near
the usual furnace control. Steering circuitry such as a
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first pair oE diodes at ~ho ~urnace control and heater current
source location and a sccond pair of diodes at the temperature
responsive element and hcater location is provided for
directing one-half of an alternating current waveform through
the furnace control and the temperature responsive element,
and the other half of the alternating current waveform through
the heater current source and the heater so that the furnace
temperature control can be independently controlled by the
temperature responsive element and the heater can be in~
dependently controlled by the heater current source by using
respective halves of the waveform for each control functio,n.
A second embodiment of the present invention achieves
the same advantages and results obtained by the first embodi- -
ment of the present invention by providing a temperature
control system utilizing a pair of temperature responsive
elements in the heated area, one beiny set at the desired
daytime temperature and the other being set at the desired
nighttime temperature. The temperature responsive elements
are activated during the appropriate period by a timer switch
which includes a pair of switched contacts. A first of t~e
s~itch contacts is associated with the nighttime temperature
responsive element by means of a diode steering circuit and
the second set of contacts is associated with the daytime
temperature responsive element by the diode steering circuit.
The steering circuit may include a first pair of diodes
associated with the timer switch and a second pair of diodes
associated with the temperature responsive elements. One
of each pair of diodes is arranged in polarity so that a '
current path for one-half of the alternating current waveform
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is providcd throu~h ono set of the timer switch contacts
thc hi~3h tc~ L~erature responsive clemcnt and the furnace
control. The other diode of each pair is arranged in polarity
so that a current path for the other half of the alternating
current waveform is provided through the other set of the
timer switch contacts, the low temperature responsive element
and the furnace control. Accordingly, each of the temperature
responsive elements is independently associated wlth the
furnace control at times determined by the closing of the
contacts of the timer switch. The second embodiment of the
present invention is also provided with an override switch
which bypasses the diode associated with the high temperature
responsive element so that the high temperature responsive -
element controls the furnace control at all times. In this
regard, when the override switch is closed, the circuit
through the furnace control will not be interrupted until
the high temperature responsive element opens the circuit,
e.g., when the high temperature is exceeded, regardless of
which timer switch contact is closed.
BRIEF DESCRIPTION OF THE l:~RAWING
Figure 1 is a schematic illustration of a first
embodiment of a temperature control system according to the
present invention; and
- Figure 2 is a schematic illustration of a second
embodiment of a temperature control system according to the
present invention.
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In Figure 1, a tcmpcraturc control system 10 is
illustrated which includes a first unit or system portion 12
which is located in the room or area in which the temperature
is to be controlled, and a second unit or system portion 14
which is located proximate the furnace. The units 12 and 14
are connected by a single pair of conductors 16 and 18 which
may be the pre-existing wiring from a conventional home
thermostat unit. The unit 14 receives standard alternating
current energy of 110-120 volts on conductors 20 and 22.
The unit 14 includes a step-down transformer 24
which converts the 110-120 volt alternating current energy to
approximately 24 volts of alternating current energy across
conductors 26 and 28. The unit 14 further includes a tem-
perature control relay or solenoid switch 30 having a relay
coil 32 and relay contacts 34 which are connected in series
with a furnace control conductor 36 which in turn is connected
to a conventional furnace control so that the furnace is
turned on to supply heat to the heated area upon powering of -
~he relay 30 which closes relay contacts 34. A spike suppression `
capacitor 37 is connected across the relay coil 32. The
unit 14 still further includes a heater control unit 38
which consists of a timer motor 40, which controls timer
contacts 42, and a variable resistor 44.
The unit 12 includes a thermostat switch 46 such
as a conventional bi-metal element which is adapted to bend
in one direction on cooling to a preset temperature to close
the switch and to bend in the other direction on heating to
a somewhat hiyher temperature. The unit 12 further includes
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a heating unit 48 which may be an incandcscent lamp bulb
or the like. Thc hea~er 98 is in thcrmal transfer rclation-
ship with the thermostatic switch 46 so that the thermostatic
switch 46 is heated by the heater 48 to make the room tem-
perature or house temperature appear higher when the heater
48 is operated.
Each of the relay coil 32, the variable resistor-
44, and the timer controlled contacts 42, the heater control
unit 38, the heater 48, and the thermostatic switch 46 are
connected to the two conductors 16 and 18 and the alternating
current source on conductors 26 and 28 by a steering circuit
which includes diodes 50, 52, 54 and 56. More particularly,
the diode 50 is connected in parallel with the relay 32
and the spike suppression capacitor 37 and is connected in
series with the supply line 26 and the conductor 16. The
diode 52 is connected in parallel with a series connection
.of the variable resistor 44 and the timer controlled switch
42, and in series with the supply conductor 28 and the con-
ductor 18. The diode 54 is connected in series with the heater
48, and across the existing conductors 16 and 18 so that it is
in parallel with the temperature responsive switch 46. The
diode 56 is connected in series with the temperature responsive
switch 46, and across the conductors 16 and 18 so that it is
in parallel with the heater 48.
In view of the above connection of the diodes, it
will be appreciated that the positive-going portion of the
potential waveform on supply line 26 provides a current
which flows through diode 50, diode 54, heater 48, timer
controllcd contacts 42, and the variable resistor 44 to
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thè other supply line 28. Negligible current flows through
the temperature controlled relay coil 32 since the voltage
drop across the forward-biased diode SO is very small, and
no current flows through the termostatic switch 46 since the
diode 56 is reversed biased.
O When a positive-going portion of the potential
waveform appears on the supply line 28, a current flows
through the diode 52, the ~hermostatic switch 46, the diode
56, and the temperature controlled relay coil 32 to the
other supply line 26. Negligible current flows through the
adjustable resistor 44 and the timer controlled switch 42
since the voltage drop across the forward-biased diode 52 is
very small, and no current flows through the heater 48 since
the diode 54 is back biased.
- In view of the above, it will be appreciated that
the time-varying, alternating current voltage waveform pro-
vided by the step-down transformer 24 on lines 26 and 28 is
divided into two time displaced portions, with one portion
being directed through the circuit including the thermostatic
switch 46 and the temperature controlled relay 32 and the
other portion being directed through the heater 48~ the
timer controlled switch 42, and the heater control variable
resistor 44. As a result, the furnace and the heater 48 can
be independently controlled.
In operation, the user sèts the thermostat switch
46 for the appropriate daytime room temperature. As explained
above, the thermostatic switch 46 operates in conjunction
with ~he temperature control unit 30 to control the operation
of the furnace through the opening and closing o~ the furnace
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control switch 34. The user als~ set~ the timer motoX so
that the switch 42 is closed during the nighttime hours and
sets the variable resistor 44 to establish the number o~
degrees of reduction of the nighttime temper~ture in the
heated area. Preferably, the variable resistor is calibrated
in degrees. For example, the calibr~tion can be between 0
and 20 degrees reduction in nighttime temperature with
increasing resistance establishing a decreasing number o~
degrees of reduction of the nighttime temperature and infinite
resistance, i.e. an open at the resistor 44, providing no
reduction in nighttime temper~ture. If desired, a switch 45
may ~e placed in series with the ~ariable resistor 44 which
is openable to provide a means for overriding the automatic
nighttime temperature reduction. Alternatively, or in
addition to the switch 45, a switch 55 may be placed in
series with the diode 54 and the heater 48 which is openable
to override the automatic nighttime reduction. By opening
either the switch 45 or the switch 55, the heater circui~ is
open-circuited so that the heater will not receive energizing
current.
During the periods in which the timer controlled
switch 42 is closed, current will flow through the heater 48
in an amount determined by the setting of the variable
resistor 44 to cause supplemental heating of the temperature
responsive switch 46. The supplemental heating of the
temperature responsive switch 46 makes the apparent temperature
o~ the heated area to appear high~r than the actual temperature.
Accordingly,! the temperature responsive switch 46 will
xeact to cause a decrease in the actual temper~ture o~ the
heated area in accordance with the amount o~ heating of the
temperature responsive switch 46 by the heater 48, and
accordingly, in accordance with the amount of current flowing
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through the heater 48 as established by the settin~ o~ the
variable resistor 44. The closing and opening o~ the tem-
perature responsive switch 46 is responsible for the closin~
and opening of the relay switch 34 so ~s to turn the ~urnace
on whenever the temperature falls below the set temperature
and turn the furnace off when the temperature rises above a
temperature slightly above the set temperatureO
In Figure 2, a second embodiment of a temperature
control system 60 is illustrated which includes a first unit
or system portion 62 which is located in the room or area in
which the temperature is to be controlled, and a second unit
or system portion 64 which is located proximate the furnace.
The units 62 and 64 are connected by a single pair of con-
ductors 16 and 18 which may be the pre-existing wiring from
a conventional home thermosta~ unit. The unit 64 receives
standard alternat~ng current energy of 110-120 volts on
conductors 70 and 72. ,'
The unit 64 includes a step-down transformer 74
which converts the 110-120 volt alternating current energy
to approximately 24 volts of alternating current energy
,across conductors 76 and 78. The unit 64 further includes a
temperature-control relay or solenoid switch 80 having a
relay coil 82 and relay contacts 84 which are connected in :
series with a furnace control conductor 86 which in turn is
connected to a conventional furnace control so that the
furnace is turned on to supply heat to the heated area upon
powering of the relay 80 which closes relay contacts 84. A
spike suppression and iltering capacitor 87 i~ connected
across the relay coil 82. The unit 64 stlll furthex includes
a dual thermostat control unit having a timer solenoid 90
which controls a nighttime timer contact 92 and a da~time
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timer contact 94. The contacts 92 and 94 are synchxonousl~
opened and closed fo~ mutually respective pexiods by a single
mechanical connection as schematically illust~ted, i.e.,
contact 92 opens when contact 94 closes and Vise Versa.
The unit 62 includes a pair of thermostat switches
96 and 98 with each switch 96 and 98 having, for example, a
conventional bi-metal element which is adapted to bend in
one direction on cooling to a preset temperature to close
the switch and to bend in the other direction on heating to
a somewhat higher temperature to open the switch. The thermo-
stats 96 and 98 are preferably mounted in the same enclosure
and are marked for day and nighttime temperatures. Each of
the thermostats 96 and 98 may be independentl~ set to the
desired temperature for daytime and nighttime, respectively.
Each of the rela~ coil 82, the timer controlled
contacts 92 and 94, and the thermostatic switches 96 and 98
are connected to the two conductors 16 and 18 and he alternating
current source on conductors 76 and 78 by a steering circuit
which includes diodes 100, 102, 104 and 106. More particularly,
the diode 100 is connected in series with d~ytime contacts
94 of the dual thermostat control unit 88 and is connected
in parallel with the nighttime contacts 92 of the dual
thermostat control unit 88. The diode 102 is connected in
series with the nighttime contacts 92 of the dual thermostat
control unit 88 and is connected in parallel with the day-
time c~ntacts 94 o the dual thermostat control unit 88.
~he diode 104 is connected in series with the low temperature
thermostat 98 in parallel with the hi~h temperature thermostat
96. The diode 106 i.s connected in series with the high
temperature thermostat 96 and ln parallel with the low tem-
perature thermostat 98.
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In view of the above conncction of diodes, it will
be appreciated that the positive-going portion of the potential
waveform Oll supply line 76 provides a current which flows
through the furnace control 82, the d.iode 106, the daytime
or high temperature thermostat 96, the diode 100, and the
daytime~ timer controlled contacts 94 ~presuming the contacts
94 are closed in the timer solenoid 90) to the other supply
line 78. During the positive half-wave on line 76, no current
flows through the nighttime or low temperature thermostatic
switch 98 since the diode 104 is reverse biased.
When a positive-going portion of the potential
waveform appears on the supply line ~78, a current flows
through the nighttime timer controlled contacts 92 (presuming
the contacts 92 are closed by the timer solenoid 90), the
nighttime or low temperature thermostatic switch 98, the
diode 104 and the furnace control coil 82 to the other
supply line 76. During the positive half-wave on line 78, no
current flows through the daytime or high temperature thermostatic
switch 96 since the diode 106 is reverse biased.
In view of the above, it will be apprecia~ed that j .
the time-varying, alternating current voltage waveform pro-
vided by the step-down transformer 74 on lines 76 and 78 is
divided into two time-displaced portions, with one portion
being directed through the circuit including the low tem-
perature thermostatic switch 98, the nighttime contacts 92 of
the timer switch 88, and the temperature-control furnace
relay 82, and the other portion being directed through the
high temperature thermostatic switch 98, the daytime contacts
9~ of thc timer switch 88 and the furnace relay 82. As a
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rcsult, thc furnace can be indepcndcn-tly controlled at
respective timcs, as sct by thc clock-controlled switch 88,
by the high and low temperature thermostats 96 and 98,
respectively.
In operation, the user sets the thermostatic
switches 96 and 98 for the appropriate daytime and nighttime
room temperatures, respectively. As explained above, the
thermostatic switch 96 operates in conjunction with the
temperature control unit 80 to control the operation of the
furnace through the opening and closing of the furnace
control switch 84. The user also sets the timer solenoid 90
so that the contacts 92 are closed during the nighttime
hours and the contacts 94 are opened during the daytime
hours, and conversely, so that the contacts 92 are open
during the daytime hours and the contacts 94 are closed
during the daytime hours.
The control unit 62 is further provided with an
override switch 108 which is connected in parallel with the
diode 106 so as to provide bi-directional current flow
through the daytime or high temperature thermostat 96 when
it is closed. Closing of the override switch 108 eliminates
the control function whereby the temperature is reduced
during the nighttime hours. This is due to the fact that
the furnace control switch 84 will be closed at any time
there is current flowing through the solenoid coil 82, and
in turn, current will flow through the solenoid coil at any
time the temperature in the heated area is below the temperature-
set at the high temperature thermostat 96. In this regard,
consider the nighttime hours at which tim~ the daytime timer
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controllcd contacts 9~ are open and the ni~httimc timex
control contacts 92 are closed which would normally result
in operation of the furnace control 80 under the control of
the low temperature thermostat 98. ynder those conditions,
diode 106 would normally prevent any current from passing
throug~ the high temperature thermostat 96 since it will be
reverse biased. When the override switch 108 is closed,
this current is no lon~er blocked by the diode 106 so that
it will also pass through the high temperature thermostat 96
(presuming the contacts thereof are closed). So long as the
temperature is below the temperature set by the high tem- i
perature thermostat 96, the opening and closing of the low
temperature thermostat 98 will have no effect on the opexation
of the furnace since current will be continuously supplied
to the furnace control solenoid coil 82 through the high
temperature thermostat 96. Whenever the temperature in the
heated area rises above the set temperature of the high
temperature thermostat 96, the switch of the high temperature
thermostat 96 will open to in~errupt the current through the
furnace control solenoid coil 82 to turn off the furnace.
At this time, it is presumed that the temperature set on the
low temperature thermostat 98 has alread~ been exceeded so
that the switch of the low temperature thermostat 98 will
already be open. Accordingly, the high temperature thermo-
stat 96 will control the temperature in the heated area
regardless of the opening and closing of the timer controlled
contacts 92 and 94.
In view of the above description of the temperature
control systcm according to the present invention, it will
bc appreciated that thc system of this invcntion uses few
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components and that thc componcnts used are available at
low cost. Consequently, the system c~n be constructed at
low cost. Importantly, the system is adapted to utilize
the existing two conductors in the wiring system of con-
ventional thermostats so th~t the temperature control system
according to the present invention may be easily installed
at low cost.
It is to be understood that the foregoing des- -
cription is that of the preferred embodiment of the invention.
Various changes and modifications may be made without de-
parting from the spirit and scope of the invention as defined
by the appended claims.
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