U.S. patent application number 10/801313 was filed with the patent office on 2005-09-22 for temperature sensing device.
This patent application is currently assigned to Johnson Controls Technology Company. Invention is credited to Drees, Kirk H., Kautz, Thomas O..
Application Number | 20050209813 10/801313 |
Document ID | / |
Family ID | 34980762 |
Filed Date | 2005-09-22 |
United States Patent
Application |
20050209813 |
Kind Code |
A1 |
Kautz, Thomas O. ; et
al. |
September 22, 2005 |
Temperature sensing device
Abstract
A temperature sensing device includes a first temperature sensor
configured for mounting to a structure at a first distance relative
to the structure. The temperature sensing device also includes a
second temperature sensor configured for mounting to the structure
at a second distance relative to the structure. The temperature
sensing device also includes a processor coupled to the first and
second temperature sensors and configured to estimate a third
temperature based on the first and second temperatures and the
distance separating the first and second temperature sensors.
Inventors: |
Kautz, Thomas O.; (Mequon,
WI) ; Drees, Kirk H.; (Cedarburg, WI) |
Correspondence
Address: |
Chad E. Bement
Foley & Lardner LLP
777 East Wisconsin Avenue
Milwaukee
WI
53202-5306
US
|
Assignee: |
Johnson Controls Technology
Company
|
Family ID: |
34980762 |
Appl. No.: |
10/801313 |
Filed: |
March 16, 2004 |
Current U.S.
Class: |
702/130 ;
374/E17.015; 374/E7.042 |
Current CPC
Class: |
G01K 17/20 20130101;
H05K 3/366 20130101; G01K 7/42 20130101; H05K 2201/10151 20130101;
H05K 2201/10598 20130101; H05K 1/189 20130101; G01K 7/427 20130101;
H05K 2201/048 20130101; H05K 1/147 20130101 |
Class at
Publication: |
702/130 |
International
Class: |
H05B 001/02 |
Claims
1. (canceled)
2. The temperature sensing device of claim 4, wherein the first and
second temperature sensors are mounted in a housing.
3. The temperature sensing device of claim 4, wherein the second
distance is greater than the first distance.
4. A temperature sensing device comprising: a first temperature
sensor configured for mounting to a structure at a first distance
relative to the structure and configured to sense a first
temperature; a second temperature sensor configured for mounting to
the structure at a second distance relative to the structure and
configured to sense a second temperature; and a processor coupled
to the first and second temperature sensors and configured to
estimate a third temperature based on the first and second
temperatures and the distance separating the first and second
temperature sensors, wherein the third temperature is an estimate
of a temperature at a third distance from the structure, the third
distance being greater than the first and second distances.
5. (canceled)
6. The method of claim 10, further including coupling a processor
to the first and second temperature sensors, and wherein the third
temperature is calculated by the processor.
7. The method of claim 6, wherein the first and second temperature
sensors are mounted in a housing.
8. The method of claim 7, wherein the processor is mounted in the
housing.
9. The method of claim 10, wherein the second distance is greater
than the first distance.
10. A method of sensing temperatures in a room, comprising:
mounting a first temperature sensor to a structure in the room at a
first distance relative to the structure; mounting a second
temperature sensor to the structure at a second distance relative
to the structure; measuring a first temperature with the first
temperature sensor, measuring a second temperature with the second
temperature sensor, and estimating a third temperature from the
first and second temperatures, wherein the third temperature is an
estimate of a temperature at a third distance from the structure,
the third distance being greater than the first and second
distances.
11. (canceled)
12. (canceled)
13. A temperature sensing device, comprising: a housing; a first
temperature sensor mounted within the housing and configured to
sense a first temperature; a second temperature sensor mounted
within the housing and spaced apart from the first temperature
sensor, and configured to sense a second temperature; and a
processor coupled to the first temperature sensor and the second
temperature sensor and configured to estimate a third temperature
using the first temperature and the second temperature, wherein the
first temperature sensor is positioned proximate to a first surface
of the housing and the second temperature sensor is positioned
proximate to a second surface of the housing spaced apart from the
first surface, and wherein the housing is configured to be mounted
to a structure of a building such that the first surface is
adjacent to a surface of the structure of the building.
14. The temperature sensing device of claim 13, wherein the first
temperature is the temperature at or near the surface of the
structure of the building.
15. The temperature sensing device of claim 14, wherein the
structure of the building is a wall.
16. The temperature sensing device of claim 15, wherein the third
temperature is an air temperature of a room including the wall.
17. (canceled)
18. A temperature sensing device, comprising: a housing; a first
temperature sensor mounted within the housing and configured to
sense a first temperature; a second temperature sensor mounted
within the housing and spaced apart from the first temperature
sensor, and configured to sense a second temperature; and a
processor coupled to the first temperature sensor and the second
temperature sensor and configured to estimate a third temperature
using the first temperature and the second temperature, wherein the
third temperature is estimated from the first temperature and the
second temperature using an extrapolation function, and wherein the
extrapolation function is a linear extrapolation function.
19. The temperature sensing device of claim 21, wherein the
extrapolation function is a non-linear extrapolation function.
20. The temperature sensing device of claim 18, wherein the
extrapolation function includes a correction factor.
21. A temperature sensing device, comprising: a housing; a first
temperature sensor mounted within the housing and configured to
sense a first temperature; a second temperature sensor mounted
within the housing and spaced apart from the first temperature
sensor, and configured to sense a second temperature; and a
processor coupled to the first temperature sensor and the second
temperature sensor and configured to estimate a third temperature
using the first temperature and the second temperature, wherein the
third temperature is estimated from the first temperature and the
second temperature using an extrapolation function, and wherein the
extrapolation function includes a correction factor, and wherein
the correction factor is based on estimated environmental or
structural conditions of a building.
22. A temperature sensing device, comprising: a housing; a first
temperature sensor mounted within the housing and configured to
sense a first temperature; a second temperature sensor mounted
within the housing and spaced apart from the first temperature
sensor, and configured to sense a second temperature; and a
processor coupled to the first temperature sensor and the second
temperature sensor and configured to estimate a third temperature
using the first temperature and the second temperature, wherein the
temperature sensing device is a thermostat configured to be used
with a climate control system.
23. The temperature sensing device of claim 22, wherein the climate
control system is a heading, ventilating, and air conditioning
system.
24. The temperature sensing device of claim 22, wherein the
processor is mounted within the housing.
25. (canceled)
26. (canceled)
27. A method comprising: measuring a first temperature using a
first temperature sensor mounted within a housing; measuring a
second temperature using a second temperature sensor mounted within
the housing and spaced apart from the first temperature sensor; and
estimating a third temperature from the first temperature and the
second temperature using a processor coupled to the first
temperature sensor and the second temperature sensor, wherein the
third temperature is estimated from the first temperature and the
second temperature using an extrapolation function, and wherein the
extrapolation function is a linear extrapolation function.
28. The method of claim 30, wherein the extrapolation function is a
non-linear extrapolation function.
29. The method of claim 27, wherein the extrapolation function
includes a correction factor.
30. A method comprising: measuring a first temperature using a
first temperature sensor mounted within a housing; measuring a
second temperature using a second temperature sensor mounted within
the housing and spaced apart from the first temperature sensor; and
estimating a third temperature from the first temperature and the
second temperature using a processor coupled to the first
temperature sensor and the second temperature sensor, wherein the
third temperature is estimated from the first temperature and the
second temperature using an extrapolation function, and wherein the
extrapolation function includes a correction factor, and wherein
the correction factor is based on estimated environmental or
structural conditions of a building.
31. The method of claim 30, wherein the first temperature sensor is
positioned proximate to a first surface of the housing and the
second temperature sensor is positioned proximate to a second
surface of the housing.
32. The method of claim 31, wherein the housing is configured to be
mounted to a structure of a building such that the first surface is
exposed to a surface of the structure of the building.
33. The method of claim 32, wherein the first temperature is the
temperature at or near the surface of the structure of the
building.
34. The method of claim 33, wherein the structure of the building
is a wall.
35. The method of claim 34, wherein the third temperature is an air
temperature of a room including the wall.
36. (canceled)
37. (canceled)
38. A temperature sensing device, comprising: a housing; a first
temperature sensing means mounted within the housing and configured
to sense a first temperature; a second temperature sensing means
mounted within the housing and spaced apart from the first
temperature sensing means, and configured to sense a second
temperature; and means coupled to the first temperature sensor and
the second temperature sensor for estimating a third temperature
from the first temperature and the second temperature, wherein the
first temperature sensor is positioned proximate to a first surface
of the housing and the second temperature sensor is positioned
proximate to a second surface of the housing, and wherein the
housing is configured to be mounted to a structure of a building
such that the first surface is adjacent to a surface of the
structure of the building.
39. The temperature sensing device of claim 38, wherein the first
temperature is the temperature of the surface of the structure of
the building.
40. The temperature sensing device of claim 39, wherein the
structure of the building is a wall.
41. A temperature sensing device, comprising: a housing; a first
temperature sensing means mounted within the housing and configured
to sense a first temperature; a second temperature sensing means
mounted within the housing and spaced apart from the first
temperature sensing means, and configured to sense a second
temperature; and means coupled to the first temperature sensor and
the second temperature sensor for estimating a third temperature
from the first temperature and the second temperature, wherein the
third temperature is an air temperature of a room including the
wall.
42. A temperature sensing device, comprising: a housing; a first
temperature sensing means mounted within the housing and configured
to sense a first temperature; a second temperature sensing means
mounted within the housing and spaced apart from the first
temperature sensing means, and configured to sense a second
temperature; and means coupled to the first temperature sensor and
the second temperature sensor for estimating a third temperature
from the first temperature and the second temperature, wherein the
temperature sensing device is a thermostat configured to be used
with a climate control system.
43. The temperature sensing device of claim 42, wherein the climate
control system is a heating, ventilating, and air conditioning
system.
44. A temperature sensing device comprising: a first temperature
sensor configured to sense a first temperature; a second
temperature sensor spaced apart from the first temperature sensor,
and configured to sense a second temperature; and a processor
coupled to the first temperature sensor and the second temperature
sensor and configured to: estimate a heat transfer rate associated
with at least one of the first temperature and the second
temperature; and determine an air temperature set point based on
the heat transfer rate.
Description
BACKGROUND
[0001] The present description relates generally to temperature
sensing devices such as thermostats, etc. More specifically, the
present description relates to temperature sensing devices
configured to compensate for mounting surface temperature
effects.
[0002] Climate control systems, such as heating, ventilating, and
air conditioning (HVAC) systems, typically include one or more
thermostats to monitor, for example, an ambient air temperature
within a particular room or zone within a building to provide
feedback as to whether the air temperature of the room needs to be
adjusted to satisfy a predetermined set point. The thermostat is
typically configured such that a temperature sensor is housed
within an enclosure to sense the temperature of the air passing
over, through, or in contact with the enclosure. The climate
control system may then compare this air temperature to the
predetermined set point to determine if the air temperature of the
room needs to be adjusted to satisfy the predetermined
setpoint.
[0003] For convenience, the thermostat may be mounted to a wall or
other surface within the room or zone. However, when the thermostat
is mounted to the surface of an outside wall or another location
where the wall surface is significantly warmer or colder than the
air temperature of the room or zone, there may be substantial
differences between the air temperature measured by the thermostat
and the actual ambient air temperature of the room or zone.
Further, air flow through the thermostat may be minimal due to a
low profile enclosure designed such that the thermostat is
minimally noticeable and does not project undesirably from the wall
or other mounting location. Under these conditions, the climate
control system may perform inefficiently because the temperature
measured by the thermostat may not be the ambient air temperature
of the room, but rather a temperature somewhere between the air
temperature of the room and the wall surface temperature. Thus
there is need for an improved temperature sensing device with the
capability to compensate for mounting surface temperature
effects.
SUMMARY
[0004] According to a first exemplary embodiment, a temperature
sensing device includes a first temperature sensor configured for
mounting to a structure at a first distance relative to the
structure, and a second temperature sensor configured for mounting
to the structure at a second distance relative to the structure.
The temperature sensing device also includes a processor coupled to
the first and second temperature sensors and configured to estimate
a third temperature based on the first and second temperatures and
the distance separating the first and second temperature
sensors.
[0005] According to a second exemplary embodiment, a method of
sensing temperatures in a room includes mounting a first
temperature sensor to a structure in the room at a first distance
relative to the structure, mounting a second temperature sensor to
the structure at a second distance relative to the structure,
measuring a first temperature with the first temperature sensor,
measuring a second temperature with the second temperature sensor,
and estimating a third temperature from the first and second
temperatures.
[0006] According to a third exemplary embodiment, a temperature
sensing device includes a housing, a first temperature sensor
mounted within the housing and configured to sense a first
temperature, and a second temperature sensor mounted within the
housing and spaced apart from the first temperature sensor, and
configured to sense a second temperature. The temperature sensing
device also includes a processor coupled to the first temperature
sensor and the second temperature sensor and configured to estimate
a third temperature using the first temperature and the second
temperature.
[0007] According to a fourth exemplary embodiment, a method
includes measuring a first temperature using a first temperature
sensor mounted within a housing, measuring a second temperature
using a second temperature sensor mounted within the housing and
spaced apart from the first temperature sensor, and estimating a
third temperature from the first temperature and the second
temperature using a processor coupled to the first temperature
sensor and the second temperature sensor.
[0008] According to a fifth exemplary embodiment, a temperature
sensing device includes a housing, a first temperature sensing
means mounted within the housing and configured to sense a first
temperature, and a second temperature sensing means mounted within
the housing and spaced apart from the first temperature sensing
means, and configured to sense a second temperature. The
temperature sensing device also includes means coupled to the first
temperature sensor and the second temperature sensor for estimating
a third temperature from the first temperature and the second
temperature.
[0009] According to a sixth exemplary embodiment, a temperature
sensing device includes a first temperature sensor configured to
sense a first temperature and a second temperature sensor spaced
apart from the first temperature sensor, and configured to sense a
second temperature. The temperature sensing device also includes a
processor coupled to the first temperature sensor and the second
temperature sensor and configured to estimate a heat transfer rate
associated with at least one of the first temperature and the
second temperature; and determine an air temperature set point
based on the heat transfer rate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 illustrates a temperature sensing device according to
an exemplary embodiment.
[0011] FIG. 2A is a diagram which schematically illustrates the
electrical components of temperature sensing device of FIG. 1
according to an exemplary embodiment.
[0012] FIG. 2B is a diagram which schematically illustrates the
electrical components of the temperature sensing device of FIG. 1
according to another exemplary embodiment.
[0013] FIG. 3 illustrates a temperature sensing device mounted to
an exterior wall of a building according to an exemplary
embodiment.
DETAILED DESCRIPTION
[0014] FIG. 1 illustrates a temperature sensing device 100
according to one exemplary embodiment. In one embodiment,
temperature sensing device 100 is a thermostat, such as a
wall-mounted electronic thermostat configured for use with a
climate control system to measure the air temperature of a room. In
other embodiments, temperature sensing device 100 may be adapted
for use with other systems or locations. Temperature sensing device
100 includes a housing 102, temperature sensors 104 and 106, and a
processor 108. Temperature sensing device 100 may be generally used
to sense a first temperature and a second temperature and to
estimate a third temperature using the first temperature and the
second temperature. More specifically, temperature sensing device
100 may be used to compensate for external temperature effects
resulting from the location of temperature sensing device 100 by
measuring a first temperature and a second temperature, and
estimating the third temperature based on the first temperature and
the second temperature.
[0015] Housing 102 is configured to provide a structure within
which temperature sensors 104 and 106, and optionally processor
108, may be mounted and enclosed. In the illustrated embodiment,
processor 108 is shown as being enclosed within housing 102. In
another embodiment, processor 108 is located within another device
or controller remotely located and/or external to housing 102.
Housing 102 is made of a rigid material such as a plastic or metal
or other material suitable to protect the internal components of
housing 102. In one embodiment, portions of housing 102 may be made
of a thermally conductive material such that at least one of the
temperatures sensed by temperature sensors 104 and 106 may be
sensed by conduction through housing 102'. In another embodiment,
housing 102 may include one or more openings or vents to facilitate
the flow of air through temperature sensing device 100 once it has
been mounted such that at least one of the temperatures sensed by
temperature sensors 104 and 106 may be sensed by convection through
housing 102.
[0016] Housing 102 is further configured to be mounted to a
structure. In the illustrated embodiment, housing 102 is configured
to be mounted to the surface of a structure of a building, such as
a wall, floor, ceiling, column, or other structure, using any
suitable mounting hardware or other means of attachment. The
structure to which temperature sensing device 100 is mounted may
be, for example, an exterior wall or other structure for which the
temperature of the surface to which temperature sensing device 100
is mounted is different from, for example, the air temperature of a
room or other area which includes or is exposed to the structure
and in which temperature sensing device 100 is mounted.
[0017] Housing 102 may be any suitable size or shape depending on
the particular application. For example, in the illustrated
embodiment, housing 102 is an essentially rectangular hollow
protrusion with a low profile such that housing 102 does not
significantly extend beyond the surface of a structure, such as a
wall, to which it is mounted. In this embodiment, housing 102 is
shaped such that it has a surface 110 and a surface 112 spaced
apart from surface 110. In the illustrated embodiment, housing 102
is formed from a mounting base 116 and a mating cover 118 such that
mounting base 116 includes surface 110 and mating cover 118
includes surface 112. In other embodiments, housing 102 may be
formed from additional pieces, or may be a single piece.
[0018] Surface 110 is configured to be adjacent to a surface of a
structure, such as a wall, to which housing 102 is mounted. Surface
112 is configured to be spaced apart from the surface of the
structure and exposed to a temperature at a distance from the
surface of the structure, such as the temperature of the air at a
distance from the surface of a wall to which temperature sensing
device 100 is mounted. Preferably, surface 112 is spaced apart from
surface 110 such that the distance between surface 110 and surface
112 is maximized while maintaining an overall low profile for
temperature sensing device 100. For example, the embodiment shown
in FIG. 1 includes a protrusion 114 extending from mating cover 118
which is configured to maximize the spacing between surface 110 and
surface 112 while maintaining an overall low profile of temperature
sensing device 100. In other embodiments, protrusion 114 may be
eliminated, such that mating cover 118 is substantially planar.
[0019] Temperature sensors 104 and 106 may be mounted within
housing 102, and may be any suitable temperature sensor. For
example, in one embodiment, temperature sensors 104 and 106 may be
resistance thermal detectors (RTDs). In another embodiment,
temperature sensors 104 and 106 may be thermistors. In one
embodiment temperature sensors 104 and 106 may be electrical or
electronic devices that provide an analog output signal. In another
embodiment, temperature sensors 104 and 106 may be electrical or
electronic devices that provide a digital output signal.
[0020] Temperature sensors 104 and 106 are configured to sense
temperatures at different locations within housing 102. For
example, in the illustrated embodiment, temperature sensor 104 is
mounted proximate to surface 110 and temperature sensor 106 is
spaced apart from temperature sensor 104 and mounted proximate to
surface 112. Preferably, the spacing between temperature sensors
104 and 106 is the maximum possible spacing that housing 102 will
permit. For example, in the illustrated embodiment, housing may be
approximately 35 millimeters between surface 100 and surface 112,
with temperature sensor 104 mounted on the inside of a 2 millimeter
thick base 116, and with temperature sensor 106 mounted on the
inside of a 1 mm thick cover 118. Of course, in other embodiments,
other spacings between temperature sensors 104 and 106 may be
optimal.
[0021] Temperature sensor 104 may be configured to sense the
temperature at or near the surface of a structure, such as a wall
to which housing 102 is mounted, and to which mounting base 116 and
surface 110 are adjacent. Temperature sensor 106 may be configured
to sense the temperature of the air to which mating cover 118 and
surface 112 are exposed. In another embodiment, temperature sensor
106 may be placed directly behind mating cover 118 in order to
position temperature sensor 106 as close as possible to the air to
which mating cover 118 and surface 112 are exposed (i.e., as far as
possible from the wall to which housing 102 is mounted), and to
minimize the response time required for temperature sensor 106 to
detect changes in temperature of the air to which mating cover 118
and surface 112 are exposed. In the illustrated embodiment, the
temperatures sensed by temperature sensors 104 and 106 are sensed
primarily by the conduction of these temperatures through housing
102. In another embodiment, housing 102 may also include openings
or vents to permit the flow of air through housing 102, and
temperature sensor 106 may be mounted within housing 102 such that
it is spaced apart from temperature sensor 104 while being exposed
to the flow of air such that the temperature of the air flowing
through housing 102 is sensed.
[0022] While the illustrated embodiment shows both sensors 104 and
106 mounted within housing 102, other mounting locations are
possible. For example, in one embodiment, temperature sensor 106
may be mounted outside housing 102. In another embodiment,
temperature sensing device 106 may be mounted on an extension to
housing 102 to increase the distance between temperature sensor 104
and 106. In yet another embodiment, temperature sensors 104 and 106
may be mounted in separate housings, so long as they are both in
communication with processor 108.
[0023] Processor 108 is coupled to temperature sensors 104 and 106
and may be any suitable processor. Processor 108 is configured to
receive a temperature measurement from temperature sensor 104 and a
temperature measurement from temperature sensor 106. In the
illustrated embodiment, processor 108 is shown as being coupled to
temperature sensors 104 and 106 and mounted within housing 102.
FIG. 2A illustrates a block diagram of this configuration according
to one exemplary embodiment. In this embodiment, temperature
sensors 104 and 106 provide analog output signals to
analog-to-digital (A/D) converters 220 and 222. A/D converter 220
is coupled to processor 108 and provides a digital version of the
analog output signal from temperature sensor 104 to processor 108.
A/D converter 222 is coupled to processor 108 and provides a
digital version of the analog output signal from temperature sensor
106 to processor 108. In another embodiment, the outputs of
temperature sensors 104 and 106 may be multiplexed such that a
single A/D may be used. Processor 108 is mounted within housing 102
and is coupled to communication port 224 such that it may
communicate digital data or information via digital bus 226 to a
controller 228 or other external device or system, such as a
climate control system. In another embodiment, temperature sensors
104 and 106 provide a digital output signal such that
analog-to-digital (A/D) converters 220 and 222 are not
necessary.
[0024] In another embodiment, processor 108 is coupled to
temperature sensors 104 and 106, but is located external to housing
102. FIG. 2B illustrates a block diagram of this configuration
according to one exemplary embodiment. In this embodiment,
temperature sensors 104 and 106 provide analog output signals to
processor 108, which is externally located in, for example,
controller 228 or other external device or system, such as a
climate control system. A/D converter 220 is coupled to processor
108 and provides a digital version of the analog output signal
received from temperature sensor 104 to processor 108. A/D
converter 222 is coupled to processor 108 and provides a digital
version of the analog output signal received from temperature
sensor 106 to processor 108. In another embodiment, temperature
sensors 104 and 106 provide a digital output signal such that
analog-to-digital (A/D) converters 220 and 222 are not
necessary.
[0025] Processor 108 is also configured to use the temperature
measurements from temperature sensors 104 and 106 to estimate a
third temperature. For example, in one embodiment processor 108 may
be configured to estimate the temperature of an air mass in a room
or other area in which temperature sensing device 100 is mounted
using temperature measurements from temperature sensors 104 and
106. Because temperature sensing device 100 may be located on the
boundary surface of the room air mass, neither temperature sensor
104 nor temperature sensor 106 may be sufficiently exposed to the
actual temperature of the air mass. Additionally, temperature
sensing device 100 may further be mounted to the surface of a
structure, such as an exterior wall, such that it is exposed to
various external or other temperature effects. Accordingly, in this
embodiment processor 108 may be configured to estimate the third
temperature from the temperature measurements from temperature
sensors 104 and 106 by compensating for the various external
temperature effects due to the mounting location of temperature
sensing device 100.
[0026] The third temperature may be estimated from the temperature
measurements from temperature sensors 104 and 106 in a number of
ways. For example, in one embodiment, the third temperature is
estimated using a predetermined extrapolation function which
defines an approximate mathematical relationship between the
temperature measurements from temperature sensors 104 and 106 and
the third temperature to be estimated. In other embodiments,
methods other than mathematical extrapolation may be used
alternatively or in addition to the extrapolation function.
[0027] The extrapolation function may be a linear extrapolation
function, or alternatively, a non-linear extrapolation function.
The particular choice of either a linear or non-linear
extrapolation function depends upon the particular application
and/or location of temperature sensing device 100, as well as the
desired level of accuracy. For example, the extrapolation function
may be selected based on known or estimated environmental (e.g.,
airflows, etc.) or structural conditions (e.g., building materials,
etc.) where temperature sensing device 100 is located. In one
embodiment, where the air temperature distribution across a room in
which temperature sensing device 100 is located is expected to be
approximately linear based on known environmental or structural
conditions (e.g., low airflow velocities through the room or area
in which temperature sensing device 100 is mounted, or through
temperature sensing device 100 itself), a first order linear
extrapolation function of the form y=mx+b may be used to estimate
the third temperature, where y is the temperature to be estimated,
m is a predetermined coefficient, x is the mathematical difference
between the temperatures sensed by temperature sensors 104, and
106, and b is the temperature sensed by temperature sensor 104. In
other embodiments, a non-linear extrapolation function or a more
complex linear extrapolation function may be used to compensate for
additional or more complex factors such as, for example, erratic
airflows in the room or area in which temperature sensing device
100 is mounted, or through temperature sensing device 100 itself,
or different materials in either temperature sensing device 100 or
in the exterior structure of the building structure to which
temperature sensing device 100 is mounted. In other embodiments,
the extrapolation function may also include additional terms or
variables to accommodate additional temperature sensors or other
inputs depending on the desired accuracy.
[0028] Any number of extrapolation functions may be used to
estimate the third temperature. For example, in one embodiment,
temperature sensing device 100 may use a first linear extrapolation
function where the temperature sensed by temperature sensor 104 is
lower than the temperature sensed by temperature sensor 106, and a
second linear extrapolation function where the temperature sensed
by temperature sensor 104 is higher than the temperature sensor 106
to account for differing thermodynamic conditions to which
temperature sensing device 100 is exposed. In other embodiments,
additional or fewer extrapolation functions may be used.
[0029] The extrapolation function may also include one or more
predetermined coefficients which may function as correction
factors. Each correction factor may be determined based on, for
example, the shape, size, and temperature sensor locations of
device 100, as well as the magnitude of known environmental or
structural conditions such that the error of the temperature
estimate from the extrapolation function is minimized. For example,
in one embodiment using a first order linear extrapolation function
of the form y=mx+b, the coefficient m may be a predetermined
correction factor which compensates for the shape, size, and
location of the temperature sensors of temperature sensing device
100, as well as one or more known or estimated environmental or
structural conditions of a building or room in which temperature
sensing device 100 is located, such as known or estimated air flow
velocities, room dimensions, expected outdoor and indoor
temperature ranges, building materials, etc. In another embodiment,
the predetermined correction factor may be determined using
computational fluid dynamic (CFD) simulations. CFD similations
utilize the size, shape, and sensor locations of temperature
sensing device 100, various estimated or known environmental and
structural conditions, and various conservation of energy, mass and
momentum equations in order to model, for example, the air mass in
a room or area in which temperature sensing device 100 is located.
For example, the CFD simulations may determine the contours of one
or more temperature gradients due to external temperature effects
in areas where temperature sensing device 100 may be located, which
may then by used to determine each correction factor.
[0030] In this way, temperature sensing device 100 may compensate
for errors due to external or other temperature effects such as a
wall surface temperature that is significantly warmer or colder
than the air temperature of the room or zone, or minimal airflow in
the area where temperature sensing device 100 is located. Reduced
errors in temperature measurements provide, for example, more
accurate and efficient climate control system performance.
[0031] Temperature sensing device 100 may also be used to determine
air temperature set points which improve the thermal comfort of an
occupant in a room or area in which temperature sensing device 100
is located. For example, in a typical setting, thermal comfort may
be achieved when the occupant's skin temperature is in a range of
approximately 91.0 degrees Fahrenheit to 93.0 degrees Fahrenheit.
Skin temperature is related to the balance between body heat
generated by the occupant and body heat transfers in the form of
body heat losses or gains to the environment of the room or
area.
[0032] The dominant body heat transfer mechanisms are convection
and radiation. Convective body heat transfer rates are a function
of room air velocity and room air temperature. In most cases the
room air velocity is constrained within narrow limits by, for
example, the HVAC system design, and the air temperature is
measured using a temperature sensor such as a thermostat.
Accordingly, air temperature set points that provide thermal
comfort, in the absence of significant radiation heat transfer, may
be identified over time.
[0033] However, if radiation heat transfer rates are high, then
occupants will not be comfortable using these air temperature set
points. Radiation heat transfer rates are a direct function of
photon exchange rates between the occupant and the surfaces of the
room or area that encloses the occupant. The primary driving force
for photon emission is temperature, and thermal comfort problems
may occur when external surfaces of the room or area are warmer or
colder than normal. This can occur, for example, when an external
surface of a ceiling or wall associated with the room or area is in
contact with the outdoors. Temperature sensing device 100 may be
accordingly configured to sense the temperature at or around the
wall or ceiling, estimate the associated radiation heat transfer
rates, and estimate an air temperature set point to compensate for
the radiation effects. Thus, occupant comfort may be improved when
radiation heat transfer rates are high.
[0034] FIG. 3 illustrates an embodiment of temperature sensing
device 100 (shown in FIG. 1) wherein a temperature sensing device
300 is mounted to an exterior wall 350 of a building. Temperature
sensing device 300 includes a housing 302, temperature sensors 304
and 306, and a processor 308. Housing 302 is shaped such that it
has a surface 310 and a surface 312 spaced apart from surface 310.
Surface 310 is configured to be adjacent to a surface 354 of
exterior wall 350, to which housing 302 is mounted, and surface 312
is configured to be spaced apart from surface 354 of exterior wall
350 and exposed to an air temperature at a distance from surface
354. Temperature sensor 304 is mounted proximate to surface 310 of
housing 302, and temperature sensor 306 is mounted proximate to
surface 312 of housing 302. Temperature sensor 304 is configured to
sense the temperature T.sub.1 at or near surface 354 of exterior
wall 350, to which housing 302 is mounted, and to which surface 310
is adjacent. Temperature sensor 306 in this embodiment is
configured to sense the temperature T.sub.2 of the air at a
distance from surface 354. Temperature sensing device 300 is
configured to estimate temperature T.sub.1A of the air mass inside
the room or area including exterior wall 350 using the temperature
T.sub.1 of surface 354 of exterior wall 350 sensed by temperature
sensor 304, and temperature T.sub.2 of the air at a distance from
surface 354 sensed by temperature sensor 306.
[0035] In the illustrated embodiment, the temperature T.sub.OA of
the outside air is significantly lower than the temperature
T.sub.1A of the air inside a room or area including exterior wall
350. The external effect of the lower outside air temperature
T.sub.OA on the inside air temperature T.sub.1A is manifested in
the form of several temperature gradients. The temperature graph
shown in FIG. 3 illustrates various temperature gradients that may
be identified given several known or estimated environmental or
structural conditions and using CFD simulations to model the air
mass inside the room under these conditions. For example, a
temperature gradient 360 may exist across the thickness of exterior
wall 350 such that the temperature of wall 350 increases from
exterior surface 352 to interior surface 354. A temperature
gradient 362 may exist across temperature sensing device 300
between surface 310 and surface 312 of housing 302. A temperature
gradient 364 may exist between surface 312 of housing 302 and a
distance beyond surface 312 at which temperature T.sub.1A is to be
estimated. Accordingly, due to the location of temperature sensing
device 300 within a different temperature gradient than T.sub.1A,
neither the temperature sensed by temperature sensor 304 nor the
temperature sensed by temperature sensor 306 is the actual
temperature of the inside air T.sub.1A.
[0036] Temperature sensing device 300 is configured to estimate
temperature T.sub.1A from T.sub.1 and T.sub.2 using one of the
following two linear extrapolation functions:
T.sub.1A=T.sub.1+C.sub.1(T.sub.2-T.sub.1) (1)
T.sub.1A=T.sub.1+C.sub.2(T.sub.2-T.sub.1) (2)
[0037] where C.sub.1 and C.sub.2 are predetermined correction
factors. Eq. (1) is used by temperature sensing device 300 where
T.sub.1 is lower than T.sub.2, and Eq. (2) is used by temperature
sensing device 300 where T.sub.1 is higher than T.sub.2. In this
embodiment, two linear extrapolation functions are used in order to
account for differing thermodynamic conditions. Linear
extrapolation functions may used as an approximation of the
temperature distribution across the room from surface 354 to the
location where T.sub.1A is to be estimated based on, for example,
low airflow velocities in the room or through temperature sensing
device 300. Predetermined correction factors C.sub.1 and C.sub.2
may be determined using, for example, CFD simulations, including
the temperature gradients shown in FIG. 3.
[0038] According to Eq. (1), where T.sub.1 is lower than T.sub.2,
the difference between T.sub.2 and T.sub.1 is multiplied by
correction factor C.sub.1 to estimate the increase in temperature
from surface 354 to the location where T.sub.1A is to be estimated.
This quantity is then added to T.sub.1 to estimate T.sub.1A. For
example, in one embodiment, C.sub.1 may be set at 1.24, T.sub.1 may
be measured to be 56 degrees Fahrenheit, and T.sub.2 may be
measured to be 67 degrees Fahrenheit. According to Eq. (1),
T.sub.1A is estimated to be 69.64 degrees Fahrenheit, which
represents a 2.64 degree compensation of the temperature measured
by temperature sensor 306. Similarly, according to Eq. (2), where
T.sub.1 is higher than T.sub.2, the difference between T.sub.2 and
T.sub.1 is multiplied by correction factor C.sub.2 to estimate the
decrease in temperature from surface 354 to the location where
T.sub.1A is to be estimated. This quantity is then added to T.sub.1
to estimate T.sub.1A. For example, in one embodiment, C.sub.1 may
be set at 1.45, T.sub.1 may be measured to be 67 degrees
Fahrenheit, and T.sub.2 may be measured to be 56 degrees
Fahrenheit. According to Eq. (2), T.sub.1A is estimated to be 51.05
degrees Fahrenheit, which represents a 4.95 degree compensation of
the temperature measured by temperature sensor 306.
[0039] It should be understood that the construction and
arrangement of the elements of the temperature sensing device in
the exemplary embodiments are illustrative only. Although only a
few embodiments of the present invention have been described in
detail in this disclosure, many modifications are possible without
materially departing from the novel teachings and advantages of the
subject matter recited in the claims. For example, the temperature
sensing device may be adapted for use in other systems or
locations, may incorporate additional temperature sensors or other
inputs, or may include other variables or factors in the
extrapolation function. Accordingly, all such modifications are
intended to be included within the scope of the present invention
as defined in the appended claims. Unless specifically otherwise
noted, the claims reciting a single particular element also
encompass a plurality of such particular elements. The order or
sequence of any process or method steps may be varied or
re-sequenced according to alternative embodiments. In the claims,
any means-plus-function clause is intended to cover the structures
described herein as performing the recited function and not only
structural equivalents but also equivalent structures. Other
substitutions, modifications, changes and/or omissions may be made
in the design, operating conditions and arrangement of the
preferred and other exemplary embodiments without departing from
the spirit of the present invention as expressed in the appended
claims.
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