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Description  |
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TECHNICAL FIELD
This invention relates to controlling the temperature in a space, by
adjusting the operation of a heating, ventilating and/or air conditioning
system (HVAC) remotely, by ordinary telephone.
BACKGROUND ART
It may be desirable to allow the temperature of a principal residence vary
to an extreme limit when the principal residence is unoccupied by virtue
of the occupants being on a business or vacation trip, or residing at a
recreational residence (such as a ski or shore cottage). With dual
residences, the temperature of either of the residences is typically
allowed to range to some extreme limit when unoccupied, yet it is desired
to be within a comfort limit when occupied.
It is known to allow the temperature of an unoccupied hotel room to deviate
significantly from that which is comfortable for occupants. Typical
systems utilize telephone lines or auxiliary telephone lines to control
units in the individual rooms. These systems utilize auxiliary thermostats
(in addition to those used in the HVAC to control comfortable
temperatures) for the enablement of the HVAC system. Systems of this type
are shown in U.S. Pat. Nos. 4,021,615; 4,107,466; 4,174,064.
In a residence, the situation is somewhat different because the
occupied/unoccupied status of the residence is not monitored by personnel
within the same building (as is the case in hotels), and therefore the
temperature conditions for an unoccupied room cannot be changed to the
desired temperature conditions for an occupied room while the intended
occupants are not present. Instead, the adjustment of temperature within
the space must await the return of the intended occupants. Such systems
have the failing that they do not anticipate the re-occupation of a room,
but simply begin the process of temperature correction once the room is
designated as occupied.
The foregoing systems, therefore, are useless in assisting in the control
of temperatures in residences. Some systems are known for monitoring and
controlling various devices and/or conditions within a residence.
Typically, these are wired systems which are difficult or impossible to
put in place except at the time of construction of a residence.
Additionally, such systems do not address the needs of a typical
homeowner, because these systems are extremely complex, and have only a
limited capability for affecting the system remotely (such as by means of
telephone). Examples of such systems are U.S. Pat. No. 4,174,517 and U.S.
Pat. No. 4,665,544.
DISCLOSURE OF INVENTION
Objects of the invention include provision of means for adjusting the
temperature in a residence remotely, by use of ordinary telephone, which
is readily made applicable to existing residences and HVAC systems,
including HVAC systems of various types, at relatively low cost.
According to the invention, the temperature-affecting capability of an HVAC
in a building is controlled from a standard telephone located outside said
building remotely from the building by means of signals transmitted over
common carrier telephone lines.
In further accord with the invention, communication of the commands which
control the capability of the HVAC from the telephone receiving unit to
the thermostat unit may be made over a wired connection, or by low power
radio frequency or other electromagnetic radiation. According further to
the present invention, the regular thermostat of a conventional HVAC
system (such as a hot air furnace with an integral air conditioner) is
replaced by a pair of switch-selected thermostats, the selection of which
is caused remotely in response to tones transmitted by regular telephone
to the building. In accordance with the invention further, the command to
select a specific thermostat may be communicated as a function of a
standard dual tone multiple frequency tone (DTMF, the normal dialing tones
for telephones).
In accordance with another aspect of the invention, the tone command may be
utilized instead to permit or prohibit operation of an HVAC (such as a
room air conditioner or heat pump), the desired occupied temperature
setpoint of which has been preset within the unit itself.
The invention is readily implemented in a wide variety of forms, utilizing
various elements of readily available apparatus and known techniques
which, when supplemented by the teachings hereinafter, are adequate to
perform the invention in a variety of embodiments. For instance, one
embodiment utilizes readily available components and subsystems to perform
functions such as hook switch, ring detection, answering, tone decode, and
so forth. Another embodiment simply picks off a remotely generated
function command signal from within a standard (or altered) call answering
machine to cause the desired effect. One embodiment utilizes pulses to
indicate a desired change in the set point, while another embodiment
utilizes tones to designate set point without regard to current setting.
Embodiments may use stepper relays, toggle relays, bistable relays or
solid state switching.
Other objects, features and advantages of the present invention will become
more apparent in the light of the following detailed description of
exemplary embodiments thereof, as illustrated in the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a simplified block diagram of a prior art thermostatically
controlled HVAC system.
FIG. 2 is a simplified, stylized block diagram of a remotely selected
thermostatically controlled HVAC system according to the invention.
FIG. 3 is a schematic block diagram of a first embodiment of the invention.
FIG. 4 is a schematic block diagram of an alternative switch for the
embodiment of FIG. 3.
FIG. 5 is a schematic block diagram of a second embodiment of the
invention.
FIG. 6 is a partial simplified block diagram of a variation of the
embodiment of FIG. 5 using an answering machine.
FIG. 7 is a schematic block diagram of a first power-controlling embodiment
of the invention.
FIG. 8 is a partial schematic block diagram of a second power-controlling
embodiment of the invention.
FIG. 9 is a partial schematic block diagram of a third power-controlling
embodiment of the invention.
BEST MODE FOR CARRYING OUT THE INVENTION
Referring now to FIG. 1, a typical heating, ventilating and/or air
conditioning system 15, referred to hereinafter as HVAC, is interconnected
by a plurality of wires 16 with a thermostatic switch 17. The HVAC 15 may
take a variety of forms, ranging from the simplest of heating units (such
as electric baseboard heat) to more complex units (such as hot air
furnaces with combined central air conditioning). In the simplest of
systems, the thermostatic switch 17 may simply comprise a single,
bi-metallic, mercury or other thermal switch that will close when heat is
required and open when the heat demand has been satisfied. In more
complicated systems, the thermostatic switch 17 may include heating and
cooling selection switches, fan operation mode switches, and the like. The
connection between the thermostatic switch 17 and the HVAC 15 may comprise
between two and six wires 16. As is known, the setpoint (temperature of
the thermostatic switch 17 defining the heating or cooling demand) can be
adjusted only manually.
Referring to FIG. 2, a thermostatic switch assembly 20, according to one
embodiment of the invention, is mounted in place of the thermostatic
switch 17 so as to readily utilize the wires 16 for connection to the HVAC
15. The thermostatic switch assembly 20 contains two thermostatic switches
17a, 17b each of which may be as simple or as complex as the single
thermostatic switch 17 which the assembly 20 replaces. At any point in
time, only one of the thermostatic switches 17a, 17b will be connected
over the wires 16 to the HVAC 15 so as to control satisfying the heating
or cooling demand. The selection is made by at least one bistable switch
21 which is connected to the thermostatic switches 17a, 17b by suitable
wires 22. The bistable switch 21 operates to connect either of the
thermostatic switches 17a, 17b to the HVAC 15 so as to cause the
heating/cooling demand set point to be the set point preestablished on the
selected thermostatic switch.
In accordance with the invention, the switch 21 is selectively operated in
response to a command initiated at a remote regular telephone 26 which is
connected by ordinary common carrier telephone lines 27 to a telephone 28.
In a preferred embodiment, specific tones are used to indicate desired
settings of the switch 21; in that embodiment, the telephone 28 interacts
with the switch 21 through tone decode and communication means 29 which
can take a variety of forms as described hereinafter. This function
includes detecting (30) when a switch-actuating tone has been received by
the telephone 28 and communicating (31) that fact to the switch 21. If, in
a particular installation such as in a residence, the telephone is located
remotely from the location of the thermostatic switch 17 (at the end of
the wires 16), then some means must be provided to communicate between the
phone 28 and the switch 21. The detection of the tone may take place at or
near the phone 28, or at or near the switch 21. Thus, the communication
(31) may occur between the phone 28 and the tone detection (30) or the
communication (31) may occur between the tone detection (30) and the
switch 21.
The first embodiment of the invention is illustrated in FIG. 3. Therein,
the phone apparatus 28 includes a hook switch 34, a ring detector 35, and
an answer circuit 36, all of which are conventional and may be the same as
or similar to those found in call answering machines. The tone detection
30 is provided by a dual tone multiple frequency (DTMF) detector 37 and a
binary to decimal decode circuit 38. The DTMF detector 37 may be a
standard DTMF chip found in answering machines. The binary to decimal
decode circuit 38 may be a simple diode network, as is known, or may be
the decode function in a complex integrated circuit, such as the central
processor integrated circuit of a phone answering machine. In FIG. 3, when
a detected call is answered, an owner wishing to adjust his HVAC will
press a touchtone button on the phone 26 causing the complex frequencies
on the telephone line 27 to reach the DTMF detector 37 thereby enabling
one of the lines 41, 42 to signal either that a high temperature is
desired or that the low temperature is desired. The communication portion
31a of the embodiment of FIG. 3 is a toggle system which has a bistable
device such as a flip flop 45 that is in synchronism with the setting of
the bistable switch 21a (described below) and the output of which is
cross-coupled to a pair of AND gates 46, 47 so that an OR circuit 48 will
provide a switching signal on a line 49 to a transmitter 50 only when one
of the lines 41, 42 is calling for temperature which is opposite to that
being remembered by the flip flop 45. Thus, if the signal appears on the
line 41 calling for high temperature, the AND gate 46 will operate only if
there is also a signal on a line 53 from the low side of the flip flop 45.
If the flip flop 45 indicates that high temperature has already been set
in the bistable switch 21a, then the AND gate 46 is blocked so the OR
circuit does not produce a signal on the line 49. Similarly, the AND gate
47 will operate only if a signal on a line 54 indicates that the bistable
switch 21a is set into the high temperature condition. A signal on the
line 49 to the transmitter 50 also operates the flip flop to reverse its
state. The transmitter 50 can be a simple transmitter that transmits any
kind of signal whatsoever, which need not even be modulated, to a
corresponding receiver 56 which is mounted integrally with the switch 21a
and the thermostats 17a, 17b directly on the thermostat head, as described
with respect to FIG. 2 hereinbefore. The receiver may be very simple and
therefore operate on batteries so that there need not be any connection to
the thermostat head from either house power or the telephone system, other
than the signals transmitted between the transmitter 50 and the receiver
56. The receiver need only slightly amplify and detect the received signal
so as to provide a pulse to a coil 57 that will cause a known stepper
relay armature 58 to advance from one pair of contacts 59, 60 to another
pair of contacts 61, 62. This will cause the selected one of the
thermostats 17a, 17b to be connected with the wires 16 and thereby
establish control over the HVAC 15 (FIG. 2) whenever a change is indicated
by a disparity between the signal on the lines 41, 42 and the signals on
the lines 53, 54. The stepper relay may have many pairs of contacts,
alternate ones of which connect the selected thermostats.
An alternative form of switch which may be utilized in the embodiment of
FIG. 3 is the bistable switch 21b of FIG. 4. Therein, a double pole,
double throw, toggle relay utilizes one set of contacts to apply a pulse
from the receiver to a selected one of two coils 67, 68 so as to pull the
armature 69 to the left or to the right. As is known, a toggle relay does
not move the switch contacts until the armature has moved past a stable
point, so that once the moving contacts of the switches begin to move,
they will snap entirely away from one fixed contact and toward the other
fixed contact. This allows using the relay's own contacts to control which
of its coils will be energized in each case. As shown, the armature 69 has
been pulled to the left by energizing the coil 67 so that the high
temperature thermostat 17a is connected with the wires 16 and so that the
next time a pulse is received, it will be transmitted to the coil 68
through the left contact 72 thereby causing the coil 68 to pull the
armature 69 to the right and connect the low temperature relay 17b to the
right contact 73, instead, and connect the coil 67 to the receiver 56
through the right contact 74.
In the embodiments of FIGS. 3 and 4, it is desirable to provide an LED 75
that will identify when the flip flop 45 is set in one or the other
states, such as the high state as shown. Then, the synchronization between
the switch 21a, 21b may be checked by adjusting the high thermostat while
the fan is in the "auto" position to see if the fan turns on and off in
response to temperature adjustments. Synchronization may then be achieved
by flipping the flip flop 45 by means of applying a suitable polarity
voltage to it through a manual switch 76 while blocking that voltage by
means of a diode 77 from operating the transmitter 50. In the embodiment
of FIG. 4, synchronization may be had by pressing a manual lever 78, which
forces the toggle switch into the high position. The switch 76 and/or
lever 78 may also be used to select the desired thermostat locally, by the
occupant of the building. Of course, there are numerous other ways in
which synchronization may be achieved, maintained, verified and adjusted.
In FIG. 5, a second embodiment of the invention illustrates several changes
from the embodiments of FIGS. 3 and 4. The first change is that the
communication function 31b occurs between the phone function 28 and the
tone detection 30. In such a case, a transmitter 80 and corresponding
receiver 81 must be selected so as to transmit any and all of the multiple
frequencies used for the dual tone. The transmitter and receiver (80, 81)
may conveniently be the standard modules utilized in portable telephones,
but any simple AM system is usable. Thus, the information in the tone
generated by the operator at phone 26 (FIG. 2) is communicated into
proximity with the thermostat so that the tone decode function 30 can
provide high and low commands directly to a bistable switch 21c, rather
than relying on the toggle function of the embodiment of FIGS. 3 and 4. In
FIG. 5, only the contacts 71 and 73 of a bistable switch 21c are utilized
since toggling need not be controlled by the switch itself. This
embodiment avoids the necessity of checking and reestablishing
synchronization once in a while, which is offset, however, by the need for
additional power to operate the circuitry 30. This will result in higher
consumption of batteries, unless the thermostat is near enough to a source
of electric power so that the circuits 30 need not be battery operated. A
lever 82 may be utilized to manually select the desired thermostat from
within the building itself. Since the contacts 72, 74 (FIG. 4) are not
used for toggling the bistable switch 21c in FIG. 5, it need not be a
toggling switch (that is, one with snap action) but need only be a
bistable switch which will remain in whichever position it is placed by
energizing one of the coils until the next time the other of the coils is
energized. FIG. 5 also indicates that the two thermostats may be used for
a normal, occupied temperature (N) and an abnormal, vacant temperature
(V). In summer, the vacant thermostat may be set high (e.g., 85.degree.)
and the normal temperature set low (e.g., 72.degree.); in winter, the
vacant thermostat may be set low (e.g., 60.degree.) and the normal
temperature set high (e.g., 70.degree.). Thus, the temperature command can
select between high and low temperatures or it can select between normal
and vacant temperatures.
FIG. 6 illustrates an embodiment of the invention which is similar to that
of FIG. 5 except that it uses a call answering machine 83 to provide the
telephone and tone decode functions of the apparatus 34-38 of FIGS. 3 and
4, and it is assumed in FIG. 6 that the telephone call answering machine
is mounted in the immediate vicinity of the thermostat so that it can be
directly connected by wires 41a, 41b which perform the communication
function 31c. The manner of achieving the embodiment of FIG. 6 is to
utilize signals on the pins of the central processor integrated circuit 84
or other points in the circuit of a typical call answering machine which
cause functions such as playback of the message or of a memo (where memo
is playing back a message created internally at the answering machine
rather than from incoming phone calls). Simply tapping onto these pins or
other circuit points can provide signals which may be designated also as
the high and low temperature demand signals on lines 41a, 42b which are
identical to the decoded signals on the lines 41 and 42 in the embodiment
of FIG. 3. Selecting functions like play and memo always allows the option
of pressing the correct tone for either playing incoming messages or
playing memos (either alone or after doing the other) so as to select the
desired thermostat. In order to prevent normal operation of the answering
machine from switching thermostats when that is not desired, a switch 85
can be utilized to break the ground line and thus leave the switch 21c
permanently set in one position or the other when the building is occupied
and automatic switching is not desired. Of course, the embodiments of
FIGS. 3, 4 and 6 may be combined, using the answering machine 83 to
provide the inputs on lines 41 and 42 to the toggle system.
Referring now to FIG. 7, a different aspect of the invention utilizes the
answering machine 83 to control the bistable switch 21c within a power
control unit 90 in which the switch 21c selectively connects an outlet 91
with power applied through a line cord from a power-receiving plug 92. By
plugging the power cord 93 of an HVAC unit such as an air conditioner 94
into the outlet 91, the HVAC unit can be caused to turn on and off, and
when on, will cycle around its previously set, internal thermostatic
switch, in the known fashion.
FIG. 8 illustrates a variation of FIG. 7 in which the switch 21a is used,
along with the toggle system of FIG. 3, in place of the switch 21c, and in
which the HVAC unit is a heater 95 instead of an air conditioning unit 94.
If desired, the HVAC unit could be a combination heater/air conditioner,
so that turning it on will cause whichever response (heating, cooling) has
previously been set in the unit, about the setpoint of the internal
thermostatic switch of the unit, as is known. Of course, the switch 21b
could be used in FIG. 8.
Another embodiment of the invention provides for additional binary to
decimal decoding of the binary signals provided by the DTMF detector in a
call answering machine utilizing codes which are not already utilized in
the answering machine for the normal telephone functions typically found
in answering machines. Typically, there are about eight DTMF combinations
unused for remote control in an answering machine, which can be decoded to
energize wires equivalent to the wires 41a, 41b of FIGS. 6 and 7 to
perform only the remote switching functions described therein.
Referring to FIG. 9, a very simple power-controlling embodiment of the
invention responds to a single command signal on the line 41 to cause the
transmitter 50 to send a signal to the receiver 56 which simply pulls the
armature of a single coil bistable relay 21d to the left so as to connect
the outlet 91 with the power-receiving plug 92. The relay may be preset in
the off state, when leaving the building, by means of a lever 99.
Although not disclosed herein, the control elements for other functions of
the HVAC 15 which are contained within the thermostatic switches 17a, 17b
may similarly be switched by additional contacts ganged to the contacts
disclosed with respect to the setpoint function. On the other hand, if
both thermostats have fan control switches, and both fan control switches
are set in the same position (either ON or AUTO), then switching of these
functions is not required. In any event, such considerations are not
relevant to the invention.
The switches used herein need not be magnetically operated, with mechanical
contacts (relays) as disclosed, but may be (and in future embodiments
preferably will be) solid state switches which in the case of the toggle
embodiments of FIGS. 3, 4 and 8 will comprise combinations of flip flops
and gates enabled thereby (functionally akin to the apparatus 45-49, 53,
54 in FIG. 3); in the case of the non-toggling embodiments of FIGS. 5-7,
the gates would be controlled by a set/reset bistable device rather than
controlled with a toggling flip flop 45. The gates may comprise field
effect transistors. Since only small signals are involved, this is easily
achieved with presently available technology. Thus, the conductive paths
for connecting the selected thermostat to the HVAC may either be
mechanically actuated switch contacts, or electronic circuit paths.
Thus, although the invention has been shown and described with respect to
exemplary embodiments thereof, it should be understood by those skilled in
the art that the foregoing and various other changes, omissions and
additions may be made therein and thereto, without departing from the
spirit and scope of the invention.
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