Note: Descriptions are shown in the official language in which they were submitted.
CA 02714583 2014-02-24
INVENTION TITLE
Programmable water heater thermostat controller
Priority Claim
This patent application claims priority from provisional U.S. patent
application
entitled "Programmable water heater thermostat controller", having an
application number
61/241,480 filed on September 11, 2009, which was subsequently converted to
non-
provisional U.S. patent application with the same title, having an application
number
12/877156 filed on September 08, 2010, which is now an issued U.S. patent with
patent
number 8,550,369.
FIELD OF INVENTION
The present invention relates to controlling the thermostat on both electric
and gas
powered water heaters based on user programmed settings.
BACKGROUND OF INVENTION
Water heaters come with a thermostat to adjust the temperature of water. When
the
set temperature is reached, the burner in gas powered water heater or the
electric coil in
electric water heater is turned off. When the temperature drops below the set
temperature,
the water heater is turned on again. This process repeats all the time. The
user sets the
temperature high enough to get hot water during periods of peak usage even on
the coldest
day of the year. This temperature is maintained during the day as well as
night when there
is not much need for hot water. People seldom change the setting of the
thermostat. Hence
the high temperature is maintained even during summer. This results in wastage
of fuel.
This also shortens the life of the water heater. There is a need for a
programmable
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thermostat that can be programmed to heat water in the morning to the required
high
temperature, then turn down the thermostat during daytime when there is no one
in the
house to use hot water, turn it up again to a moderate temperature in the
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evening for dinner time usage and turn it down for the night. Since there are
already
millions of water heaters in use, the programmable thermostat should be easy
to install on
an existing water heater.
In U.S. patent number 6,920,843, William Wilson uses a solenoid in the gas
supply
line to interrupt supply of gas. It has two drawbacks. The first is that the
user will have to
get the unit installed by a licensed plumber. The second drawback is that the
manufacturer
warranty may be voided since we are tampering with the original design of the
product. So
this is not a practical one. In U.S. patent numbers 7,380,522 and 6.375,087,
the system
has to be built in by the manufacturer. It cannot be attached to the millions
of water heaters
already in use.
SUMMARY OF INVENTION
The primary objective of the present invention is to conserve energy by way of
a
programmable controller that can vary the temperature setting at different
times of the day.
Another objective of the present invention is to make it easy for anyone to
attach the
unit to an existing water heater without the need to call a plumber.
A third objective is to make the unit cost effective for the consumers to buy
and use
it.
The foregoing objectives are attained by having a programmable microcontroller
vary the temperature setting by turning the temperature control knob based on
user
preprogrammed temperature settings at user preprogrammed times of the day.
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In this respect, before explaining at least one embodiment of the invention in
detail, it
is to be understood that the invention is not limited in its application to
the details of
construction and to the arrangements of the components set forth in the
following
description or illustrated in the drawings. The invention is capable of other
embodiments
and of being practiced and carried out in various ways. Also, it is to be
understood that the
phraseology and terminology employed herein are for the purpose of description
and
should not be regarded as limiting.
As such, those skilled in the art will appreciate that the concept, upon which
this
disclosure is based, may readily be utilized as a basis for the designing of
other structures,
methods and systems for carrying out the several purposes of the present
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig 1 is the prior art of a storage type water heater with a temperature
control unit.
Fig 2 is the front view of the preferred embodiment of the programmable water
heater thermostat controller attached to the temperature control unit on the
water heater.
Fig 3 is the rear view of the preferred embodiment of the programmable water
heater
thermostat controller with the internal parts revealed.
Fig 4 is a side view of the drive means.
Fig 5 is the side view of the position sensing means that is used to sense the
position of the temperature control knob on the water heater.
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Fig 6 is a block diagram of the electronic circuit board used to control the
rotation of
the temperature control knob.
Fig 7 is a schematic circuit diagram to control the direction of rotation of
the geared
electric motor shaft using two single pole double throw relays..
Fig 8 is a schematic circuit diagram to control the direction of rotation of
the geared
electric motor shaft using four opto-isolators.
Fig 9 is the block diagram of the remote user interface.
Fig 10 is the flowchart of the decision process used by the microcontroller to
rotate
the temperature control knob at different times of the day. It also shows the
logic used to
program the time and temperature information by the user. Vacation mode
decision logic is
also illustrated.
Fig 11 shows the flowchart of the decision process used by the first
transmitter /
receiver means.
DETAILED DESCRIPTION OF THE INVENTION
Fig 1 is the prior art of a storage type water heater, 1. Unit 1 has a
temperature
control unit 2, to control the temperature of water heated. Temperature
control unit 2 has a
temperature control knob 3 that the user turns to set the desired temperature
for hot water.
Arc 4 above the temperature control knob shows the direction the temperature
control knob
should be turned to increase water temperature. In this illustration, the
temperature control
knob should be turned in a counter clockwise direction to increase water
temperature.
Position indicator, 5, on the temperature control knob 3, shows the
temperature setting with
respect to arc 4.
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Figure 2 shows the front view of the preferred embodiment of a programmable
water
heater thermostat controller of the present invention mounted on top of
temperature control
unit 2. The programmable water heater thermostat controller of the present
invention
consists of a faceplate, 11, with a first display means, 12, to display the
current time, or, at
the time of programming, the program information, which will be discussed
later. Faceplate,
11, has a window, 13, through which the temperature control knob 3 and the
temperature
indicating arc 4 can be seen. A plurality of switches, 7, are used as first
user input means.
These switches are used to program user desired time and corresponding user
desired
temperature information. The components of the present invention are mounted
on the
reverse side of faceplate 11 as shown in Fig 3.
Referring to Fig 2, Fig 3, Fig 5 and Fig 6, an electronic circuit board, 28,
with a
microcontroller 50 on it, is connected by wire to said first display means, 12
and a first
transmitter / receiver means, 23. The plurality of switches, 7, are also
mounted on the
electronic circuit board, 28. On the periphery of window 13 are two
subsystems, numbered
19 and 24. Subsystem 19, henceforth called the position sensing means,
consists of a
driven pinch roller 49, fixedly attached to shaft 45 of a potentiometer 26.
The potentiometer
has three terminals, 46, 47 and 48. Terminal 46 is connected to +5 volts
supply. Terminal
48 is connected to ground. Terminal 47 is connected to analog to digital input
pin 56 of
microcontroller 50. Since the resistance varies when the potentiometer knob is
turned, it is
a good candidate as a rotation sensor. The position sensing means is fixedly
mounted on
the first end of a sensor mount, 20, while the second end, 22, of sensor mount
sticks out
from faceplate, 11. Sensor mount 20 is attached rotatably to faceplate 11 at
second pivot
point 21. A wire, 27, with three conductors, connects potentiometer 26 with
said electronic
circuit board, 28.
Referring to Fig 2, Fig 3 and Fig 4, drive means, 24, is used to turn
temperature
control knob, 3. Drive means 24 consists of a geared electric motor, 14, and a
driver pinch
roller, 41. Shaft, 35, of the geared electric motor is rigidly connected to
said driver pinch
roller, 41.
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Drive means 24 is fixedly mounted on the first end of a driver mount 15 while
second end,
18, of the driver mount sticks out from faceplate 11. Driver mount 15 is
attached rotatably to
faceplate 11 at first pivot point 17. A tension spring, 16, with a first end
and a second end
connects driver mount, 15, with sensor mount, 20. First end of tension spring
is connected
to driver mount 15 at first attachment point, 29. Second end of tension spring
is connected
to sensor mount, 20, at second attachment point, 30. The spring tension keeps
driver pinch
roller, 41, and driven pinch roller, 49, pressed against temperature control
knob 3 when the
programmable water heater thermostat controller is mounted on temperature
control unit, 2.
A wire, 25, with two conductors, connects geared electric motor 14, to the
electronic circuit
board, 28. When the second end, 18 of driver mount and the second end, 22 of
sensor
mount are pushed toward each other, the driver pinch roller and the driven
pinch roller
disengage from the temperature control knob. This is done when the
programmable water
heater thermostat controller is installed or uninstalled from the temperature
control unit.
Fig 6 is a block diagram of the input / output connection to microcontroller,
50. The
plurality of switches, 7, are connected to a plurality of input pins, 55, on
said
microcontroller. The microcontroller accepts program time and corresponding
temperature
information from the user through said plurality of switches 7. It outputs
display information
to said first display means, 12 via a set of output pins, collectively
numbered 52. The
analog to digital input pin 56 of the microcontroller is connected to the
center tap terminal
47 of potentiometer 26. The voltage between ground and terminal 47 varies
proportional to
the rotational position of temperature control knob 3. The analog value of the
voltage on pin
56 passes through an analog to digital converter on the microcontroller to
provide a
corresponding digital value for the position of the potentiometer shaft and
thereby, the
position of the temperature control knob, 3. Output pin 65 of the
microcontroller is
connected to one terminal of relay coil in relay 57 while the other terminal
of the relay coil is
connected to the positive power supply. Similarly,
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,
output pin 66 of the microcontroller is connected to one terminal of relay
coil in relay 58
while the other terminal of the relay coil is connected to the positive power
supply. The two
relays are of the single pole double throw (SPDT) type. The direction of
rotation of the
geared electric motor is controlled by controlling power to the coils in the
two relays. The
microcontroller communicates with the first transmitter / receiver means, 23,
via input /
output pin 51.
Fig 7 is a schematic diagram of the relay contact connection with the geared
electric
motor. Each relay has two fixed contacts and one moveable contact. In relay
57, the
moveable contact, 59, is connected to terminal 31 on geared electric motor 14.
Fixed
contact 60 is connected to ground while fixed contact 61 is connected to +5
volts. Similarly,
in relay 58, the moveable contact, 62, is connected to terminal 32 on geared
electric motor
14. Fixed contact 63 is connected to ground while fixed contact 64 is
connected to +5 volts.
When the coil in relay 57 is not energized, moveable contact 59 is in
electrical
communication with fixed contact 60. When the coil in relay 57 is energized,
contact 59 is in
electrical communication with contact 61. Similarly, when the coil in relay 58
is not
energized, moveable contact 62 is in electrical communication with fixed
contact 63. When
the coil in relay 58 is energized, contact 62 is in electrical communication
with fixed contact
64.
When relay 57 and relay 58 are de-energized, the two terminals of the geared
electric motor are connected to ground. Hence the geared electric motor will
not turn. When
only relay 57 is energized by output signal on pin 65, geared electric motor
terminal 31 is at
+5 volts with respect to terminal 32. Hence the geared electric motor is
energized and turns
in one direction. Let us assume it to be clockwise direction. When only relay
58 is
energized by output signal on pin 66, geared electric motor terminal 32 is at
+5 volts with
respect to terminal 31. Hence the geared electric motor is energized but with
the polarity of
the terminals reversed. Hence the geared electric motor will turn in the
counter clockwise
direction. Thus, by controlling the output signal on pins 65 and 66 of the
microcontroller, the
direction
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of rotation of the geared electric motor and thereby, the direction of
rotation of the
temperature control knob can be controlled.
Fig 8 shows another implementation of the geared electric motor control. Here
four
opto-isolators, 67, 68, 69 and 70 are used. The opto-isolator will conduct
only when the
LED in the opto-isolator is energized. In the configuration shown in Fig 8,
the input to opto-
isolators 67 and 68 are connected to +5v power supply. The output from opto-
isolators 69
and 70 are connected to ground. The output of 67 is connected to terminal 31
of the geared
electric motor as well as the input of 70. Similarly, output of 68 is
connected to terminal 32
of the geared electric motor as well as the input of 69. Output pin 65 of the
microcontroller
is connected to control pin of both 67 and 69. Output pin 66 of the
microcontroller is
connected to control pin of both 68 and 70. When there is an output signal
only on pin 65,
opto-isolators 67 and 69 are active. This completes the circuit for the geared
electric motor
through +5v - 67 ¨ 31 ¨ geared electric motor ¨ 32 ¨ 69 ¨ ground. For this,
let us assume
that the shaft of the geared electric motor rotates in a clockwise direction.
When there is an
output signal only on pin 66, opto-isolators 68 and 70 are active. This
completes the circuit
for the geared electric motor through +5v - 68 ¨ 32 ¨ geared electric motor ¨
31 ¨ 70 ¨
ground. Since the polarity on the geared electric motor terminals is reversed,
the shaft of
the geared electric motor will now turn in a counter clockwise direction. Thus
by controlling
the output signal on pins 65 and 66 of the microcontroller, the direction of
rotation of the
geared electric motor and thereby, the direction of rotation of the
temperature control knob
can be controlled.
Fig 9 is a block diagram of remote user interface, 71. It consists of a
plurality of
switches, 74, to act as the second user input means. It also has a second
display means,
73, and a second transmitter / receiver means, 72. In this, the second
transmitter / receiver
means is designed to communicate seamlessly with the first transmitter /
receiver means.
Thus the user need not go to the basement where the water heater is generally
kept. They
can use the remote user interface from any location in the house to change the
time and
temperature settings programmed.
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Fig 10 shows the decision logic used by the microcontroller to turn the
temperature
control knob based on current time and the user desired temperature settings
stored by the
user. It also shows the decision logic used when the vacation mode is selected
by the user.
The microcontroller keeps checking its input lines to see if any user data is
coming to it to
process. If there is any user input on any of its input lines, it goes into
programming mode
to accept and store user furnished time and corresponding temperature data.
Fig 11 shows the decision logic used by the first transmitter / receiver means
to
receive data and transmit to the correct recipient.
To attach the present invention to the temperature control unit 2, on water
heater, 1,
the user presses or pushes the ends 18 and 22 protruding out from faceplate 11
toward
each other so that the drive means and the position sensing means are moved
farther
away from each other. He places the programmable water heater thermostat
controller on
top of temperature control unit, 2 and then releases the grip on 18 and 22.
Because of
tension spring, 16, driver pinch roller 41 and driven pinch roller 49 move
toward each other
and press against temperature control knob 3. The user fastens faceplate 11 to
temperature control unit with fasteners that are not shown in the diagram.
Now, when the
geared electric motor is actuated by the microcontroller through one of the
two relays, it will
turn the driver pinch roller, 41. Since the driver pinch roller is pressing
against temperature
control knob 3 due to spring tension from spring 16, temperature control knob
3 will rotate.
Since driven pinch roller, 49 is also pressing against temperature control
knob 3, driven
pinch roller 49 and hence, potentiometer shaft 45 will rotate. When shaft 45
rotates, the
voltage on center tap 47, of the potentiometer will vary. This varies the
digital output from
the analog to digital converter on the microcontroller. Thus the
microcontroller, by
comparing digital value of the potentiometer voltage with the stored digital
value, can
determine when to de-energize the relay and stop the rotation of temperature
control knob
3.
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A driver pulley can be substituted for the driver pinch roller. In this case,
a driven
pulley should be securely fastened to the top of the temperature control knob
so that the
axis of rotation of the driven pulley is substantially the same as the axis of
rotation of the
temperature control knob. A belt means will connect the driver pulley with the
driven pulley.
Based on space availability, this drive means might be advantageous. If a
positive drive is
desired, then the driver pinch roller can be substituted with a driver gear.
In that case, a
driven gear should be securely fastened to the top of the temperature control
knob so that
the axis of rotation of the driven gear is substantially the same as the axis
of rotation of the
temperature control knob. Similarly, a position sensing gear can be
substituted for the
driven pinch roller on the position sensing means such that the driven gear on
the
temperature control knob communicates rotatably with the position sensing gear
to turn the
potentiometer shaft.
Relays 57 and 58 can be substituted with opto-isolators or solid state relays
to
achieve the same function. The circuit connection for opto-isolators is shown
in Fig 8.
Similarly, for position sensing, instead of a potentiometer, optical sensors
can be used.
Thus the same function can be implemented using multiple types of components.
Every minute, when the time changes, the microcontroller checks to see if the
family
is on vacation. If not, it compares the current time against the plurality of
stored times. If it
matches any one of them, it reads the corresponding desired temperature
setting for the
temperature control knob. Then it checks the digital value for the present
position of
temperature control knob 3. Comparing the two values, it determines whether
the
temperature control knob should be turned clockwise or counter clockwise and
energizes
the appropriate relay. While the relay is energizing the geared electric
motor, the
microcontroller continually reads the potentiometer center tap voltage and
compares it with
the stored temperature setting. Once the two values match, the microcontroller
de-
energizes the relay to stop the geared electric motor.
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The microcontroller also checks continually for input from the first
transmitter /
receiver means and the first user input means. If input comes from the first
user input
means, then the display result is sent to the first display means. If input
comes from the
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first transmitter / receiver means, then the display result is sent to the
first transmitter /
receiver means.
The first transmitter / receiver means continually checks for wireless input
from a
plurality of devices with which it is configured to communicate. Some examples
of such
devices are the remote user interface and the cellular telephone. The user may
change the
program from a different part of the house using the remote user interface. Or
the user
might realize, while on the road that he has forgotten to set the unit for
vacation mode. In
that instance he might use the cellular telephone to change the mode of
operation. When
the first transmitter / receiver means receives input wirelessly, it sets
certain flags in its
memory to indicate the source of input. Then it decodes the input and presents
it to the
microcontroller. When the microcontroller responds with display information,
the first
transmitter / receiver means encodes the information and transmits it
wirelessly to the
device from which it received the input data originally. For this purpose, it
reads the status
of flags it had set previously and determines the recipient of the display
information. Then it
clears those sets of flags, getting the unit ready for next wireless input.
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