U.S. patent application number 11/131466 was filed with the patent office on 2006-11-23 for thermostat and method for operating in either a normal or dehumidification mode.
Invention is credited to Steven L. Carey, Carl J. Mueller, Bartholomew L. Toth.
Application Number | 20060260334 11/131466 |
Document ID | / |
Family ID | 37447048 |
Filed Date | 2006-11-23 |
United States Patent
Application |
20060260334 |
Kind Code |
A1 |
Carey; Steven L. ; et
al. |
November 23, 2006 |
Thermostat and method for operating in either a normal or
dehumidification mode
Abstract
The inventive thermostat provides for sensing the temperature
and humidity within the space, and responsively controlling the
operation of an air conditioning compressor and blower to maintain
the desired temperature and humidity. In a first mode, the
thermostat operates the compressor at maximum capacity and the
blower at less than maximum capacity to provide dehumidification
when the humidity level is above a set point. In a second mode, the
thermostat operates the compressor and blower at maximum capacity
to provide full cooling capacity when the sensed temperature is
more than a predetermined amount above the desired temperature
setting. The thermostat is also configured to automatically switch
from the first mode of operation to the second mode of
operation.
Inventors: |
Carey; Steven L.; (St.
Louis, MO) ; Mueller; Carl J.; (St. Louis, MO)
; Toth; Bartholomew L.; (St. Louis, MO) |
Correspondence
Address: |
HARNESS, DICKEY, & PIERCE, P.L.C
7700 BONHOMME, STE 400
ST. LOUIS
MO
63105
US
|
Family ID: |
37447048 |
Appl. No.: |
11/131466 |
Filed: |
May 17, 2005 |
Current U.S.
Class: |
62/176.6 ;
62/228.4 |
Current CPC
Class: |
F25B 2600/0253 20130101;
Y02B 30/70 20130101; F24F 2003/1446 20130101; G05D 27/02 20130101;
Y02B 30/741 20130101; F24F 2110/10 20180101; F24F 3/1405 20130101;
F24F 11/77 20180101; F24F 11/30 20180101; F24F 2110/00 20180101;
F24F 2110/20 20180101 |
Class at
Publication: |
062/176.6 ;
062/228.4 |
International
Class: |
F25B 49/00 20060101
F25B049/00; F25B 1/00 20060101 F25B001/00 |
Claims
1. A digital thermostat for controlling the operation of an air
conditioner having a variable capacity compressor and blower,
comprising: a temperature sensing means for providing a signal
indicating the temperature of a space, a humidity sensing means for
providing a signal indicating the humidity level within the space;
a processor for receiving signals from the temperature sensing and
humidity sensing means and for sending signals for controlling the
operation of the compressor and blower; the processor operative in
a first mode to operate the compressor and the blower at less than
full capacity when the sensed humidity is above the desired
humidity set point and the sensed temperature is not more than a
predetermined amount above the humidity set point; and the
processor operative in a second mode to operate the compressor at
full capacity and the blower at full capacity when the sensed
temperature is more than a predetermined amount above the desired
temperature set point.
2. The digital thermostat of claim 1, wherein the processor is
operative in a third mode to operate the compressor at less than
full capacity and the blower at full capacity when the sensed
temperature is above the temperature set point and the sensed
humidity is below the desired humidity set point.
3. The digital thermostat of claim 1, wherein the variable capacity
compressor comprises a plurality of selectable speeds.
4. The digital thermostat of claim 3, where the variable capacity
blower comprises a plurality of selectable speeds.
5. The digital thermostat of claim 3, wherein the variable capacity
blower comprises a continuously variable range of speeds.
6. The digital thermostat of claim 5, wherein the processor
switches from the first mode of operation to the second mode of
operation when the sensed humidity is above the desired humidity
set point and the sensed temperature rises more than a
predetermined amount above the temperature set point.
7. The digital thermostat of claim 6, wherein the predetermined
amount is about three degrees Fahrenheit.
8. The digital thermostat of claim 4, further comprising a display
that displays the mode of operation as Dehumidification when the
blower is operating at less than full capacity and the compressor
is operating at full capacity.
9. A digital thermostat for controlling the operation of an air
conditioner having a multi-speed compressor and blower, comprising:
a temperature sensing means for providing a signal indicating the
temperature of a space, a humidity sensing means for providing a
signal indicating the humidity level within the space; a processor
for receiving signals from the temperature sensing and humidity
sensing means and for sending signals for controlling the operation
of the compressor and blower, wherein the processor responsively
operates the compressor at the maximum speed and operates the
blower at less than the maximum speed when the sensed humidity is
above the desired humidity set point and the sensed temperature is
within a predetermined amount above the temperature set point; and
wherein the processor responsively operates the compressor at the
maximum speed and the blower at the maximum speed when the sensed
temperature is more than a predetermined amount above the desired
temperature set point.
10. The digital thermostat of claim 9, wherein the processor
operates the compressor at less than the maximum speed and the
blower at the maximum speed when the sensed temperature is above
the temperature set point and the sensed humidity is below the
desired humidity set point.
11. The digital thermostat of claim 9, wherein the compressor
comprises at least two levels of operation.
12. The digital thermostat of claim 9, wherein the compressor
includes a motor that comprises at least two speeds of
operation.
13. The digital thermostat of claim 12, wherein the blower includes
a motor that comprises at least two speeds of operation.
14. The digital thermostat of claim 13, wherein the processor
switches the blower from a less than maximum speed to the maximum
speed when the sensed humidity is above the desired humidity set
point and the sensed temperature rises more than a predetermined
amount above the temperature set point.
15. The digital thermostat of claim 14, wherein the predetermined
amount is about three degrees Fahrenheit.
16. The digital thermostat of claim 14, further comprising a
display that displays the mode of operation as Dehumidification
when the blower is operating at less than full capacity and the
compressor is operating at full capacity.
17. A digital thermostat in combination with a variable speed
compressor and a variable speed blower, the combination comprising:
a temperature sensing means for providing a signal indicating the
temperature of a space, a humidity sensing means for providing a
signal indicating the humidity level within the space; a processor
for receiving signals from the temperature sensing and humidity
sensing means and for sending signals for controlling the operation
of the compressor and blower, wherein the processor responsively
operates the compressor at the maximum speed and operates the
blower at a speed that is less than the maximum when the sensed
humidity is above the desired humidity set point and the sensed
temperature is within a predetermined amount above the temperature
set point; and wherein the processor responsively operates the
compressor at the maximum speed and the blower at the maximum speed
when the sensed temperature is more than a predetermined amount
above the desired temperature set point.
18. The combination of claim 17, wherein the processor switches
from the first mode of operation to the second mode of operation
when the sensed humidity is above the desired humidity set point
and the sensed temperature rises more than a predetermined amount
above the temperature set point.
19. A method of controlling the operation of thermostat for an air
conditioner having a variable speed compressor and blower, a
humidity sensor and a temperature sensor, the method comprising the
steps of: sensing the temperature of the space to be maintained;
sensing the humidity level of the space to be maintained;
determining if the sensed humidity level is above the desired
humidity set point; determining if the sensed temperature is above
the temperature set point but less than a predetermined amount
above the temperature set point; responsively establishing
operation of the compressor at full capacity and operation of the
blower at less than full capacity when the sensed humidity is above
the desired humidity set point and the sensed temperature is above
the temperature set point but less than a predetermined amount
above the temperature set point.
20. The method of claim 19, further comprising the steps of
establishing operation of the compressor at full capacity and the
blower at full capacity when the sensed temperature rises more than
a predetermined amount above the temperature set point.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to thermostats, and in
particular, to thermostats used for controlling climate control
systems that include a multi-stage air conditioning system.
[0002] Thermostats are used to control climate control systems to
maintain the temperature of the space conditioned by the climate
control system. The typical thermostat compares the sensed
temperature of the space with a set point temperature and activates
the climate control system to heat or cool the space to the desired
set point temperature. Some climate control systems include a
multi-stage cooling system that comprises a two speed compressor
and a two speed indoor circulator blower. This dual speed cooling
system can operate the compressor at a low speed when the demand
for cooling is low, and at a high speed when the demand for cooling
is high. Likewise, the indoor circulator blower may be operated at
a high speed for maximum cooling or at a low speed for improved
dehumidification. One method of operating a two speed system for
providing optimum dehumidification is disclosed in U.S. Pat. No.
5,303,561 to Bahel, in which a mode of operating the indoor blower
and compressor is described. When a thermostat senses both a room
temperature and humidity level that are above the desired
temperature and humidity set points, the thermostat may request the
air conditioner to operate the compressor at full capacity and the
indoor blower fan at less than full speed capacity. This slows the
circulating air flow to allow more time for heat and moisture to be
removed from the air, which provides improved dehumidification over
the normal mode of operation at high speed full compressor capacity
and maximum circulator blower speed. However, a thermostat
providing such a dehumidification mode for operating the blower at
a reduced speed will not cool the space as effectively as when the
blower is at high speed. If the temperature in the space suddenly
increases by several degrees as a result of doors left open, a
thermostat having such a dehumidification mode will operate the air
conditioner at less than full capacity and cool the space too
slowly to attain the desired temperature setting and provide
adequate comfort. The resulting uncomfortable temperature would
consequently force the occupant to input a request to this type of
thermostat to manually override the dehumidification operating
mode.
SUMMARY OF THE INVENTION
[0003] In accordance with the principles of the present invention,
various embodiments of a thermostat for controlling a variable
capacity cooling system are provided. One embodiment of a
thermostat comprises a processor for receiving input signals from a
temperature sensor and humidity sensor for sensing the temperature
and humidity within the space, and responsively providing for
operation in a first mode to operate the compressor and operate the
blower at less than full capacity when the sensed temperature and
sensed humidity are above the desired temperature and humidity set
points, and in a second mode to operate the compressor at full
capacity and the blower at full capacity when the sensed
temperature is more than a predetermined amount above the desired
temperature set point. The first mode of operating the compressor
at maximum capacity and the blower at less than maximum capacity
provides improved dehumidification when the humidity level in the
space is above the desired humidity set point. The second mode of
operating the compressor at maximum capacity and the blower at
maximum capacity provides full cooling capacity when the sensed
temperature is more than a predetermined amount above the
temperature set point, regardless of whether the humidity level is
above the desired humidity set point. The thermostat of the present
invention automatically switches between the first mode of
operation and second mode of operation as necessary to maintain the
desired temperature while also offering humidity control to provide
optimum comfort to the occupant.
[0004] In another aspect of the invention, a second embodiment of a
thermostat is provided that comprises a processor for receiving
signals from a temperature sensing means and a humidity sensing
means, and for sending signals for controlling the operation of the
compressor and blower, wherein the processor responsively operates
the compressor at the maximum speed and operates the blower at less
than the maximum speed when the sensed humidity is above the
desired humidity set point and the sensed temperature is within a
predetermined amount above the temperature set point. The processor
also responsively operates the compressor at the maximum speed and
the blower at the maximum speed when the sensed temperature is more
than a predetermined amount above the desired temperature set
point.
[0005] In yet another aspect of the present invention, some
embodiments of a thermostat can automatically switch between a
first mode of operation to provide optimum dehumidification and
second mode of operation to provide maximum cooling, to prioritize
holding the temperature of the space over dehumidification for
maintaining optimum comfort to the occupant.
[0006] Yet another aspect of the present invention is to provide a
thermostat that displays the present mode of operation of the
thermostat on a display means, such that the occupant may be
alerted of either a humidity level above the desired humidity set
point or of a temperature more than a predetermined amount above
the temperature set point.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is an illustration of a building having an air
conditioning system in connection with a thermostat according to
the principles of the present invention.
[0008] FIG. 2 is a flow chart illustrating the method of operating
a thermostat according to the principles of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0009] A thermostat for controlling a climate control system in
which embodiments of the present invention can be implemented is
indicated generally as 20 in FIG. 1. The climate control system
includes an air conditioning system having a compressor unit 22 and
a blower unit 24 each of which is capable of operating at full
capacity and at less than full capacity. The thermostat 20 controls
the operation of the air conditioning system via connections to a
compressor motor and a blower motor. The thermostat 20 further
comprises an internal or external temperature sensor 26 and an
internal or external humidity sensor 28 for sensing the temperature
and humidity within the space conditioned by the air conditioning
system. In one embodiment, the thermostat 20 comprises a processor
for receiving input signals from the temperature sensor and
humidity sensor. The thermostat is also configured to enable an
occupant to provide input to the processor of a desired temperature
set point and a desired humidity set point. The processor of the
present invention is generally a microprocessor, and is preferably
a SCC825A microcontroller manufactured by Samsung, and has an RS
485 input port pin.
[0010] In response to a signal from the temperature sensor
indicating a temperature that is above a desired temperature set
point, a program in the processor initiates signals for controlling
the activation of the compressor and blower of the air conditioning
system to cool the space. Specifically, the program in the
processor operates according to the flow chart shown in FIG. 2. At
step 100 the processor receives input signals indicating the value
of the sensed temperature T and the sensed humidity level H and
stores the values in memory. The processor then compares the sensed
temperature to the desired temperature set point at step 110. If
the sensed temperature is not greater than the set point
temperature, the processor proceeds at step 120 to decrement a
counter that is used to measure the cumulative on and off running
time of the air conditioner. If the sensed temperature is greater
than the set point temperature, the processor proceeds to step 130
to compare the sensed humidity to the desired humidity set point.
If at step 130 the sensed humidity is below the desired humidity
set point, the processor proceeds at step 160 to compare the
on-time counter to a default value. If at step 160 the counter is
not greater than the default value, which indicates that the air
conditioner had previously been running for short time periods, the
processor initiates signals at step 170 for activating relays to
operate the compressor at less than full capacity or low speed, and
to operate the blower at full capacity or high speed. This will
provide for Normal cooling capacity operation of the air
conditioner. If at step 160 the counter is above the default value,
which indicates that the air conditioner has been running for long
time periods, the processor initiates signals at step 180 for
activating relays to operate the compressor at full capacity or
high speed, and to operate the blower at full capacity or high
speed. This will provide for maximum cooling capacity of the air
conditioner. While the air conditioner is running at steps 170 or
180, the processor compares the sensed temperature to the
temperature set point at step 190. As long as the sensed
temperature is not less than the set point temperature at step 190
the air conditioner will continue to run according to the preceding
steps. If the sensed temperature is less than the set point
temperature at step 210, the processor will discontinue operation
of the compressor and blower at step 220.
[0011] If at step 130 the sensed humidity is above the desired
humidity set point, the processor proceeds at step 140 to determine
if the sensed temperature is more than a predetermined amount above
the set point temperature. In one embodiment, the predetermined
amount is about 3 degrees, but other embodiments may alternately
comprise a higher predetermined amount or a selectable amount
within a range of about 3 degrees to about 8 degrees. If at step
140 the sensed temperature is not more than three degrees above the
temperature set point, the processor initiates signals at step 150
for activating relays to operate the compressor at full capacity or
high speed, and to operate the blower at less than full capacity or
low speed. This will provide for optimum dehumidification operation
of the air conditioner. The processor will continue to operate in
this mode until the sensed temperature at step 210 falls below the
set point temperature, or the sensed temperature at step 140 rises
more than three degrees above the set point temperature. If the
demand for cooling is high, e.g., the doors to the space are left
open to allow warm air to enter the space, the optimum
dehumidification mode of operating at less than full blower speed
will not provide sufficient cooling capacity to maintain the
temperature in the space. In the example of a large social
gathering in which the doors to the space may be left open, the
temperature of the space increases at a faster rate than the blower
running at reduced capacity can keep up with. .As a result, the
temperature will over time increase above the set point
temperature. If after a period of time the temperature rises more
than three degrees Fahrenheit above the set point temperature at
step 140, the processor proceeds to step 160 to switch to the
Maximum cooling mode of operation. The second mode of operation
overcomes the inability of the first dehumidification operating
mode to maintain the temperature when demand is high, which occurs
as a result of cooling at less than full capacity. Given the time
that the air conditioner was running in dehumidification mode, the
counter value at step 160 is accordingly above the default value,
which indicates that the air conditioner has been running for a
significant time period. With the counter greater than the default
valve Ni, processor initiates signals at step 180 for activating
relays to operate the compressor at full capacity or high speed,
and to operate the blower at full capacity or high speed. This will
provide for maximum cooling capacity of the air conditioner. While
the air conditioner continues to run at step 180, the processor
compares the sensed temperature to the temperature set point at
step 190. As long as the sensed temperature is not less than the
set point temperature at step 190 the air conditioner will continue
to run. If the sensed temperature is less than the set point
temperature at step 190, the processor will discontinue operation
of the compressor and blower at step 200.
[0012] In one embodiment of a thermostat incorporating the
principles of the present invention, the thermostat may also be
configured to have a user adjustable counter value for adjusting
the time period that the air conditioner will run at reduced
capacity before switching to full cooling capacity. Likewise, the
predetermined amount above the set point temperature at which the
thermostat will switch from the dehumidification mode to the
maximum cooling mode of operation is also user adjustable within a
range. This predetermined amount may be adjusted by the user from 1
degree to 6 degrees to adjust the time period that the air
conditioner will run at reduced capacity before switching to full
cooling capacity.
[0013] The thermostat 100 may be configured to include an LCD
display that can be used to display the mode of operation of the
thermostat as either a Dehumidification mode, a Normal mode or a
Maximum Cooling mode of operation. The thermostat can then display
to the occupant the present mode of operation of the thermostat,
such that the occupant is alerted of a humidity level above the
desired humidity set point or of a temperature more than a
predetermined amount above the temperature set point. Thus, the
thermostat implementing the present invention can automatically
switch between a first mode of operation to provide optimum
dehumidification and second mode of operation to provide maximum
cooling, to prioritize maintaining the temperature of the space
over enabling humidity control to provide optimum comfort to the
occupant.
[0014] It should be noted that the thermostat LCD display is used
to display a current mode of operation and the temperature or
humidity settings of the thermostat. This information may also be
communicated through other display means such as a multi-color LED
that changes color to indicate the mode of operation. Likewise, the
inventive thermostat may not be configured to allow user adjustment
of the default counter value or predetermined amount above the set
point temperature. The thermostat may also be configured to be used
with other apparatus not disclosed in the preceding embodiments,
such as a heat pump unit in a climate control system.
[0015] Additional design considerations, readily apparent to one of
ordinary skill in the art, such as the modification of the
thermostat to provide adjustment of the predetermined amount or
default value recited above, may also improve the user's ability to
adjust or correct a cooling rate problem of the air conditioner
system. It should be apparent to those skilled in the art that
various modifications such as the above may be made without
departing from the spirit and scope of the invention. More
particularly, the apparatus may be adapted to any apparatus for
cooling a space. Accordingly, it is not intended that the invention
be limited by the particular form illustrated and described above,
but by the appended claims.
* * * * *