U.S. patent application number 10/373202 was filed with the patent office on 2004-08-26 for dual zone automatic climate control algorithm utilizing heat flux analysis.
This patent application is currently assigned to NISSAN TECHNICAL CENTER NORTH AMERICA, INC.. Invention is credited to Eisenhour, Ronald S..
Application Number | 20040164171 10/373202 |
Document ID | / |
Family ID | 32771426 |
Filed Date | 2004-08-26 |
United States Patent
Application |
20040164171 |
Kind Code |
A1 |
Eisenhour, Ronald S. |
August 26, 2004 |
DUAL ZONE AUTOMATIC CLIMATE CONTROL ALGORITHM UTILIZING HEAT FLUX
ANALYSIS
Abstract
A method for automatically controlling the climate in a
plurality of climate control zones of a cabin of an automobile
comprising at least a driver zone and a passenger zone having a
temperature sensor located in a driver side zone and at least one
conditioned air outlet vent in each of the zones, the method
comprising, obtaining various values indicative of internal and
external climate, determining outlet temperatures and mass flow
rates of at least one of a driver zone outlet and at least one of a
passenger zone outlet based at least on the above obtained values
and on other factors relating to the design of the automobile,
including a zone air crossover influence factor, providing
conditioned air to the cabin from at least one of the driver zone
outlets and at least one of the passenger zone outlets at the
determined outlet temperatures and mass flow rates.
Inventors: |
Eisenhour, Ronald S.; (West
Bloomfield, MI) |
Correspondence
Address: |
FOLEY AND LARDNER
SUITE 500
3000 K STREET NW
WASHINGTON
DC
20007
US
|
Assignee: |
NISSAN TECHNICAL CENTER NORTH
AMERICA, INC.
|
Family ID: |
32771426 |
Appl. No.: |
10/373202 |
Filed: |
February 26, 2003 |
Current U.S.
Class: |
236/49.3 ;
236/91C |
Current CPC
Class: |
B60H 1/00064 20130101;
B60H 1/0075 20130101; B60H 2001/00185 20130101 |
Class at
Publication: |
236/049.3 ;
236/091.00C |
International
Class: |
F24F 007/00 |
Claims
What is claimed is:
1. A method for automatically controlling the climate in a
plurality of climate control zones of a cabin of an automobile
comprising at least a first zone and a second zone having a
temperature sensor located in the first zone and a conditioned air
outlet vent in each of the zones, the method comprising: obtaining
a target temperature value for the first zone and the second zone;
obtaining a first zone temperature value estimate from the sensor
in the first zone; obtaining an ambient air temperature value;
obtaining a sun load heat flux value for at least one of the first
zone and the second zone; obtaining a first zone gain factor value
based at least on the first zone temperature value estimate;
automatically determining the outlet temperatures and mass flow
rates of the first zone outlet and the second zone outlet based at
least on the above obtained values and on a conduction/convection
heat transfer coefficient between the cabin and ambient air, an
effective glass area for solar load transmission, a zone air
crossover influence factor, and predetermined constraints on the
relationship of the outlet temperatures and air flow, wherein the
zone air crossover influence factor is a factor based on blending
of air in the cabin; and providing conditioned air to the cabin
from the first zone outlet and the second zone outlet at outlet
temperatures and mass flow rates correlating to the determined
outlet temperatures and mass flow rates.
2. The method of claim 1, wherein the zone air crossover influence
factor is variable and depends on an air distribution mode.
3. The method of claim 1, further including calculating an error
term and subtracting it from the second zone outlet temperature to
establish a new second zone outlet temperature, the error term
comprising a value based on the first zone target temperature
value, the first zone temperature value estimate, the mass air flow
rate of the second zone outlet, and a second zone gain factor value
based at least on the first zone temperature value estimate,
wherein the conditioned air provided to the second zone is at the
new second zone outlet temperature.
4. The method of claim 3, wherein the first zone gain factor value
and the second zone gain factor value are approximately equal when
the first zone temperature estimate is between about 20.degree. C.
and about 28.degree. C.
5. The method of claim 4, wherein the first zone gain factor value
and the second zone gain factor value vary inversely in relation to
changing first zone temperature estimates between at least the
range from about 10.degree. C. to about 20.degree. C. and between
at least the range from about 28.degree. C. to about 35.degree.
C.
6. The method of claim 5, wherein the first zone gain factor value
decreases with increasing first zone temperature estimates below
about 20.degree. C. and increases with increasing first zone
temperature estimates above about 28.degree. C.
7. The method of claim 1, further including calculating an overset
value to be added to the second zone outlet temperature value, the
overset value comprising a value based on the second zone target
temperature value, the conduction/convection heat transfer
coefficient between the cabin and the ambient air, and the mass air
flow rate, as adjusted by a value that sets the strength of the
overshoot.
8. The method of claim 1, wherein the mass flow rate of the
conditioned air provided to the first zone is about the same as the
mass flow rate of the conditioned air provided to the second
zone.
9. The method of claim 8, further including calculating a minimum
mass air flow rate based on the conduction/convection heat transfer
coefficient between the cabin and the ambient air, the second zone
target temperature value, the ambient air temperature value, the
sun load heat flux value for the second zone, the effective glass
area for solar load transmission, and a capacity temperature value
selected from a group consisting of a constant cooling device
temperature and a constant heating device temperature, and wherein
the mass air flow rate of the conditioned air delivered to the
cabin is based on the calculated minimum mass air flow rate.
10. The method of claim 9, wherein the mass air flow rate of the
air delivered to the cabin is limited to a predetermined maximum
mass air flow rate above a variable mass flow rate based on
predetermined constraints.
11. The method of claim 10, wherein the variable mass flow rate
based on predetermined constraints is substantially correlated to
various blower voltages, the maximum mass air flow rate is
substantially correlated to the blower voltage, and wherein the
maximum mass air flow rate is limited to an equivalent blower
voltage that is no greater than about 2 volts above the equivalent
voltage of the mass air flow rate based on predetermined
constraints.
12. The method of claim 1, wherein the conditioned air provided to
the cabin from the first zone outlet and the second zone outlet at
outlet temperatures and mass flow rates is equal to the determined
outlet temperatures and mass flow rates, respectively.
13. A method for automatically controlling the climate in a
plurality of climate control zones of a cabin of an automobile
comprising at least a first zone and a second zone having a
temperature sensor located in a first zone and an conditioned air
outlet vent in each of the zones, the method comprising at least
utilizing an algorithm relating to at least equations
ToD=[TGT(D)+(Ge.multidot.(TGT(D)-RMd)+K.multidot.(TGT(D)-T.sub.-
a)-q.sub.s(D).multidot.GL)/GA-R.multidot.ToPa]/(1-R) and
ToP=ToD+([TGT(P)-TGT(D)].multidot.(1+K/GA)-[q.sub.s(P)-q.sub.s(D)].multid-
ot.GL/GA)/(1-R) where: ToD=First zone outlet temperature,
ToP=Second zone outlet temperature, TGT(D)=First zone target
temperature, TGT(P)=Second zone target temperature, Ge=Gain factor,
RMd=First zone temperature estimate from sensor, q.sub.s(D)=First
zone sun load heat flux, q.sub.s(P)=Second zone sun load heat flux,
GL=Effective glass area for solar load transmission,
T.sub.a=Ambient temperature, GA=Mass air flow rate, K=Conduction or
convection heat transfer coefficient between the cabin and ambient
air, R=Zone crossover influence factor, ToPa=The second zone's true
outlet temperature, (Evaporator Temperature.ltoreq.ToPa.ltore-
q.Heater Air Outlet Temperature), the method comprising:
automatically determining ToD, ToP, and GA by solving the above
equations with predetermined constraints on the relationship of
ToD, ToP, and GA; and providing conditioned air to the cabin from
the first zone outlet and the second zone outlet at outlet
temperatures and mass flow rates correlating to the determined
outlet temperatures and mass flow rates.
14. The method of claim 13, wherein Ge'.multidot.(TGT(D)-RMd)/GA is
subtracted from the calculated value of ToP, wherein Ge' is a gain
factor less than or equal to Ge.
15. The method of claim 14, wherein Ge and Ge' are approximately
equal when the first zone temperature estimate is between about
20.degree. C. and about 28.degree. C.
16. The method of claim 15, wherein Ge and Ge' vary inversely in
relation to changing first zone temperature estimates between at
least the range from about 10.degree. C. to about 20.degree. C. and
between at least the range from about 28.degree. C. to about
35.degree. C.
17. The method of claim 16, wherein Ge decreases with increasing
first zone temperature estimates below about 20.degree. C. and
increases with increasing first zone temperature estimates above
about 28.degree. C.
18. The method of claim 13, wherein OverSet.multidot.[1+K/GA]is
added to the value of ToP, where OverSet=X.multidot.(TGT(P)-FSet),
where X is a calibration value, and where
FSet=FSet+Y.multidot.(TGT(P)-FSet), where Y is a multiplier that is
arbitrarily set to allow the FSet equation to be utilized in an
algorithm that obtains the unity value of FSet by a loop
routine.
19. The method of claim 13, further including calculating a minimum
mass air flow rate from the equation:
GA=K.multidot.(TGT(P)-Ta-q.sub.s(P).mult- idot.GL/K)/(Capacity
Temperature-TGT(P)) where Capacity Temperature is a value selected
from a group consisting of a constant cooling device temperature
and a constant heating device temperature, and wherein the mass air
flow rate of the conditioned air delivered to the cabin is based on
the calculated minimum mass air flow rate.
20. The method of claim 19, wherein the mass air flow rate of the
air delivered to the cabin is limited to a predetermined maximum
mass air flow rate above a variable mass flow rate based on
predetermined constraints.
21. The method of claim 20, wherein the variable mass flow rate
based on predetermined constraints is substantially correlated to
various blower voltages, the maximum mass air flow rate is
substantially correlated to the blower voltage, and wherein the
maximum mass air flow rate is limited to an equivalent blower
voltage that is no greater than about 2 volts above an equivalent
voltage of the mass air flow rate based on predetermined
constraints.
22. The method of claim 13, wherein the constraints include human
constraint factors that modify thermodynamic constraint factors in
the relationship of air flow and the outlet temperatures, and
wherein the method further includes repeatedly addressing the
constraints in response to incremental changes in variables in the
equations to effect a change that will result in a modification of
the outlet temperatures.
23. The method of claim 13, wherein the conditioned air provided to
the cabin from the first zone outlet and the second zone outlet at
outlet temperatures and mass flow rates is equal to the determined
outlet temperatures and mass flow rates, respectively.
24. An automatic climate control apparatus for automatically
controlling climate in a plurality of climate control zones of a
cabin of an automobile comprising at least a first zone and a
second zone, comprising: an air blower adapted to blow conditioned
air into the cabin; an air outlet vent in the first zone in fluid
communication with the air blower; an air outlet vent in the second
zone in fluid communication with the air blower; an air cooling
device and an air heating device in fluid communication with the
air blower, the first zone vent, and the second zone vent; a
temperature sensor located in the first zone adapted to provide a
temperature value estimate of the first zone; an electronic
processor device comprising a processor and a memory, wherein the
memory is adapted to store a plurality of equations, the plurality
of equations including equations for the air outlet temperatures
and mass flow rates of the first zone outlet and the second zone
outlet, the equations being based on variables including: a target
temperature value for the first zone and the second zone; a first
zone temperature value estimate; an ambient air temperature value;
a sun load heat flux value for at least one of the first zone and
the second zone; a first zone gain factor value based at least on
the first zone temperature value estimate; a conduction/convection
heat transfer coefficient between the cabin and the ambient air; an
effective glass area for solar load transmission; and a zone air
crossover influence factor, wherein the zone air crossover
influence factor is a factor based on blending of air in the cabin;
wherein the electronic processor is adapted to automatically
control and adjust mass flow rate and temperature of the air being
blown from the vents based on the equations as constrained by
predetermined constraints on the relationship of the outlet
temperatures and air flow.
25. The apparatus of claim 24, further including a device adapted
to vary the amount of air entering the cabin that has passed
through or around the air heating device.
26. An automobile having an automatic climate control system
according to claim 23.
27. The apparatus of claim 24, wherein the conditioned air provided
to the cabin from the first zone outlet and the second zone outlet
at outlet temperatures and mass flow rates is equal to the
determined outlet temperatures and mass flow rates,
respectively.
28. A climate control device for controlling at least one component
of a climate control system that controls climate in a plurality of
climate control zones of a cabin of an automobile comprising at
least a first zone and a second zone, comprising: a device adapted
to receive a signal representing mass flow rate of conditioned air
being blown into the cabin; a device adapted to output a signal to
control heating and cooling of air being blown into the cabin; a
device adapted to output a signal to control the mass flow rate of
air being blown into the cabin; a device adapted to receive a
signal representative of a sensed temperature inside the cabin; a
device storing an algorithm based on at least a plurality of
equations, the plurality of equations including equations for air
outlet temperatures and mass flow rates of first zone outlet and
second zone outlet, the equations being based on variables
including: a target temperature value for the first zone and the
second zone; a first zone temperature value estimate; an ambient
air temperature value; a sun load heat flux value for at least one
of the first zone and the second zone; a first zone gain factor
value based at least on the first zone temperature value estimate;
a conduction/convection heat transfer coefficient between the cabin
and ambient air; an effective glass area for solar load
transmission; and a zone air crossover influence factor, wherein
the zone air crossover influence factor is a factor based on
blending of air in the cabin; and a device storing a plurality of
predetermined constraints on a relationship of the first zone and
second zone outlet temperatures and air flow; wherein the control
device is adapted to automatically output a signal to control and
adjust the mass flow rate and temperature of air being blown from
the vents based on the equations as constrained by the
predetermined constraints on the relationship of the outlet
temperatures and air flows.
29. A method for automatically controlling climate in a plurality
of climate control zones of a cabin of an automobile comprising at
least a first zone and a second zone having a temperature sensor
located in the first zone and a temperature sensor located in the
second zone and an conditioned air outlet vent in each of the
zones, the method comprising: obtaining a target temperature value
for the first zone and the second zone; obtaining temperature value
estimates for the first zone and the second zone from the first
zone temperature sensor and the second zone temperature sensor
respectively; obtaining an ambient air temperature value; obtaining
a sun load heat flux value for at least one of the first zone and
the second zone; obtaining at least one of a gain factor value
based the first zone temperature value estimate and a gain factor
value based on the second zone temperature value estimate;
automatically determining outlet temperatures and mass flow rates
of the first zone outlet and the second zone outlet based at least
on the above obtained values and on a conduction/convection heat
transfer coefficient between the cabin and ambient air, an
effective glass area for solar load transmission, a zone air
crossover influence factor, and predetermined constraints on a
relationship of the outlet temperatures and air flow; wherein the
zone air crossover influence factor is a factor based on blending
of air in the cabin; and, providing conditioned air to the cabin
from the first zone outlet and the second zone outlet at outlet
temperatures and mass flow rates correlating to the determined
outlet temperatures and mass flow rates.
30. The method of claim 29, wherein the zone air crossover
influence factor is variable and depends on an air distribution
mode.
31. The method of claim 29, wherein the mass flow rate of the
conditioned air provided to the first zone is about the same as the
mass flow rate of the conditioned air provided to the second
zone.
32. The method of claim 31, further including calculating a minimum
mass air flow rate based on the conduction/convection heat transfer
coefficient between the cabin and the ambient air, the second zone
target temperature value, the ambient air temperature value, the
sun load heat flux value for the second zone, the effective glass
area for solar load transmission, and a capacity temperature value
selected from a group consisting of a constant cooling device
temperature and a constant heating device temperature, wherein the
mass air flow rate of the conditioned air delivered to the cabin is
based on the calculated minimum mass air flow rate.
33. The method of claim 32, wherein the mass air flow rate of the
air delivered to the cabin is limited to a predetermined maximum
mass air flow rate above a variable mass flow rate based on
predetermined constraints.
34. The method of claim 33, wherein the variable mass flow rate
based on predetermined constraints is substantially correlated to
various blower voltages, the maximum mass air flow rate is
substantially correlated to the blower voltage, and wherein the
maximum mass air flow rate is limited to an equivalent blower
voltage that is no greater than about 2 volts above the equivalent
voltage of the mass air flow rate based on predetermined
constraints.
35. The method of claim 29, wherein the conditioned air provided to
the cabin from the first zone outlet and the second zone outlet at
outlet temperatures and mass flow rates is equal to the determined
outlet temperatures and mass flow rates, respectively.
36. A method for automatically controlling climate in a plurality
of climate control zones of a cabin of an automobile comprising at
least a first zone and a second zone and having a temperature
sensor located in the first zone and a temperature sensor located
in the second zone and an air outlet vent in each of the zones, the
method comprising at least utilizing an algorithm relating to at
least equations:
ToD[TGT(D)+(Ge.sub.(D).multidot.(TGT(D)-RMd)+K.multidot.(TGT(D)-T.sub.a)--
q.sub.s(D).multidot.GL)/GA.sub.(D)-R.multidot.ToPa]/(1-R) and
ToP=[TGT(P)+(Ge(p).multidot.(TGT(P)-RMp)+K.multidot.(TGT(P)-T.sub.a)-q.su-
b.s(P).multidot.GL)/GA.sub.(P)-R.multidot.ToDa]/(1-R) where:
ToD=First zone outlet temperature, ToP=Second zone outlet
temperature, TGT(D)=First zone target temperature, TGT(P)=Second
zone target temperature, Ge.sub.(D)=Gain factor based on a first
zone temperature value estimate, Ge.sub.(P)=Gain factor based on a
second zone temperature value estimate, RMd=First zone temperature
estimate from sensor, RMp=Second zone temperature estimate from
sensor, q.sub.s(D)=First zone sun load heat flux, q.sub.s(P)=Second
zone sun load heat flux, GL=Effective glass area for solar load
transmission, T.sub.a=Ambient temperature, GA.sub.(D)=Mass air flow
rate of the first zone, GA.sub.(P)=Mass air flow rate of the second
zone, K=Conduction or convection heat transfer coefficient between
the cabin and ambient air, R=Zone crossover influence factor,
ToPa=The second zone's true outlet temperature, (Evaporator
Temperature.ltoreq.ToPa.ltoreq.Heater Air Outlet Temperature),
ToDa=The first zone's true outlet temperature, (Evaporator
Temperature.ltoreq.ToDa- .ltoreq.Heater Air Outlet Temperature),
the method comprising: automatically determining ToD and ToP, and
GA by solving the above equations with predetermined constraints on
a relationship of ToD, ToP, GA.sub.(D) and GA.sub.(P); and
providing conditioned air to the cabin from the first zone outlet
and the second zone outlet at outlet temperatures and mass flow
rates correlating to the determined outlet temperatures and mass
flow rates.
37. The method of claim 36, wherein the conditioned air provided to
the cabin from the first zone outlet and the second zone outlet at
outlet temperatures and mass flow rates is equal to the determined
outlet temperatures and mass flow rates, respectively.
38. The method of claim 37, wherein GA(D) is equal to or about
equal to GA.sub.(P).
39. The method of claim 37, wherein Ge(D) is equal to or about
equal to Ge.sub.(P).
40. The method of claim 38, further including calculating a minimum
mass air flow rate from the equation:
GA.sub.(D/P)=K.multidot.(TGT(P)-Ta-q.sub-
.s(P).multidot.GL/K)/(Capacity Temperature-TGT(P)) where Capacity
Temperature is a value selected from a group consisting of a
constant cooling device temperature and a constant heating device
temperature, and wherein the mass air flow rate of the conditioned
air delivered to the cabin is based on the calculated minimum mass
air flow rate.
41. The method of claim 40, wherein the mass air flow rate of the
air delivered to the cabin is limited to a predetermined maximum
mass air flow rate above a variable mass flow rate based on
predetermined constraints.
42. The method of claim 40, wherein the variable mass flow rate
based on predetermined constraints is substantially correlated to
various blower voltages, the maximum mass air flow rate is
substantially correlated to the blower voltage, and wherein the
maximum mass air flow rate is limited to an equivalent blower
voltage that is no greater than about 2 volts above the equivalent
voltage of the mass air flow rate based on predetermined
constraints.
43. An automatic climate control apparatus for automatically
controlling climate in a plurality of climate control zones of a
cabin of an automobile comprising at least a first zone and a
second zone, comprising: an air blower adapted to blow conditioned
air into the cabin; an air outlet vent in the first zone in fluid
communication with the air blower; an air outlet vent in the second
zone in fluid communication with the air blower; an air cooling
device and an air heating device in fluid communication with the
air blower, the first zone vent, and the second zone vent; a
temperature sensor located in the first zone adapted to provide a
temperature value estimate of the first zone; an electronic
processor device comprising a processor and a memory, wherein the
memory is adapted to store a plurality of equations, the plurality
of equations including equations for the air outlet temperatures
and mass flow rates of the first zone outlet and the second zone
outlet, the equations being based on variables including: a target
temperature value for the first zone and the second zone; a first
zone temperature value estimate; an ambient air temperature value;
a sun load heat flux value for at least one of the first zone and
the second zone; a first zone gain factor value based at least on
the first zone temperature value estimate; a conduction/convection
heat transfer coefficient between the cabin and ambient air; an
effective glass area for solar load transmission; and a zone air
crossover influence factor, wherein the zone air crossover
influence factor is a factor based on blending of air in the cabin;
wherein the electronic processor is adapted to automatically
control and adjust the mass flow rate and the temperature of the
air being blown from the vents based on the equations as
constrained by predetermined constraints on the relationship of the
outlet temperatures and air flow.
44. The method of claim 1, wherein the first zone is a driver zone
and the second zone is the passenger zone.
45. The method of claim 13, wherein the first zone is a driver zone
and the second zone is the passenger zone.
46. The apparatus of claim 24, wherein the first zone is a driver
zone and the second zone is the passenger zone.
47. The apparatus of claim 28, wherein the first zone is a driver
zone and the second zone is the passenger zone.
48. The method of claim 29, wherein the first zone is a driver zone
and the second zone is the passenger zone.
49. The method of claim 36, wherein the first zone is a driver zone
and the second zone is the passenger zone.
50. The apparatus of claim 43, wherein the first zone is a driver
zone and the second zone is the passenger zone.
51. A method for automatically controlling the climate in a
plurality of climate control zones of a cabin of an automobile
comprising at least a first zone and a second zone having a
temperature sensor located in a first zone and an conditioned air
outlet vent in each of the zones, the method comprising at least
utilizing an algorithm relating to at least equations
ToD=[TGT(D)+(Ge.multidot.(TGT(D)-RMd)+K.multidot.(TGT(D)-T.sub.-
a)-q.sub.s(D).multidot.GL)/GA-R.multidot.ToP]/(1-R) and
ToP=ToD+([TGT(P)-TGT(D)].multidot.(1+K/GA)-[q.sub.s(P)-q.sub.s(D)].multid-
ot.GL/GA)/(1-R) where: ToD=First zone outlet temperature,
ToP=Second zone outlet temperature, TGT(D)=First zone target
temperature, TGT(P)=Second zone target temperature, Ge=Gain factor,
RMd=First zone temperature estimate from sensor, q.sub.s(D)=First
zone sun load heat flux, q.sub.s(P)=Second zone sun load heat flux,
GL=Effective glass area for solar load transmission,
T.sub.a=Ambient temperature, GA=Mass air flow rate, K=Conduction or
convection heat transfer coefficient between the cabin and ambient
air, R=Zone crossover influence factor, the method comprising:
automatically determining ToD, ToP, and GA by solving the above
equations with predetermined constraints on the relationship of
ToD, ToP, and GA; and providing conditioned air to the cabin from
the first zone outlet and the second zone outlet at outlet
temperatures and mass flow rates correlating to the determined
outlet temperatures and mass flow rates.
52. A method for automatically controlling climate in a plurality
of climate control zones of a cabin of an automobile comprising at
least a first zone and a second zone and having a temperature
sensor located in the first zone and a temperature sensor located
in the second zone and an air outlet vent in each of the zones, the
method comprising at least utilizing an algorithm relating to at
least equations:
ToD=[TGT(D)+(Ge.sub.(D).multidot.(TGT(D)-RMd)+K.multidot.(TGT(D)-T.sub.a)-
-q.sub.s(D).multidot.GL)/GA.sub.(D)-R.multidot.ToP]/(1-R) and
ToP=[TGT(P)+(Ge.sub.(P).multidot.(TGT(P)-RMp)+K.multidot.(TGT(P)-T.sub.a)-
-q.sub.s(P).multidot.GL)/GA.sub.(P)-R.multidot.ToD]/(1-R) where:
ToD=First zone outlet temperature, ToP=Second zone outlet
temperature, TGT(D)=First zone target temperature, TGT(P)=Second
zone target temperature, Ge.sub.(D)=Gain factor based on a first
zone temperature value estimate, Ge.sub.(P)=Gain factor based on a
second zone temperature value estimate, RMd=First zone temperature
estimate from sensor, RMp=Second zone temperature estimate from
sensor, q.sub.s(D)=First zone sun load heat flux, q.sub.s(P)=Second
zone sun load heat flux, GL=Effective glass area for solar load
transmission, T.sub.a=Ambient temperature, GA.sub.(D)=Mass air flow
rate of the first zone, GA.sub.(P)=Mass air flow rate of the second
zone, K=Conduction or convection heat transfer coefficient between
the cabin and ambient air, R=Zone crossover influence factor, the
method comprising: automatically determining ToD and ToP, and GA by
solving the above equations with predetermined constraints on a
relationship of ToD, ToP, GA.sub.(D) and GA.sub.(P); and providing
conditioned air to the cabin from the first zone outlet and the
second zone outlet at outlet temperatures and mass flow rates
correlating to the determined outlet temperatures and mass flow
rates.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
[0001] The invention is related to the inventions disclosed in U.S.
Pat. No. 5,832,990 and U.S. Pat. No. 5,995,889, the contents of
which are incorporated by reference herein in their entirety.
BACKGROUND OF THE INVENTION
[0002] An example of a climate control system of the prior art is
seen in FIG. 1. The system comprises an electronic microprocessor
controller 26 which receives a temperature signal from an interior
air temperature sensor 28. It also receives signals from a solar
heat sensor 30 and an ambient air temperature sensor 32. The
controller 26 will develop a voltage, as shown at 34, for
controlling the speed of the blower 36 as air is passed by the
blower over an evaporator 38 and a heater core 40. In a
conventional fashion, the air flow that passes over the heater core
40 can be controlled by a blend door 42, the opening of which is
controlled by an air mix controller 44. The processor 26 in a
conventional fashion will activate the blend door as indicated
schematically at 46.
[0003] Air is distributed to the upper control panel area as shown
at 48 or to the lower floor area of the vehicle as shown at 50,
depending upon the position of door 52, which is under the control
of an air mode controller 54. The controller 26 activates the air
mode controller 54 as shown at 56.
[0004] The vehicle operator may set the desired temperature with a
conventional control head, the output of which is distributed to
the controller as an input.
[0005] Intake air mass flow is also determined by the electronic
controller 26, as indicated by control line 60.
[0006] The electronic controller may be one of a variety of known
digital microprocessors (e.g., an 8-bit, single-chip
microcomputer). It includes a read-only memory (ROM) in which the
heat flux control equation is stored. It has the usual
random-access memory registers (RAM) that receive information from
the sensors before it is looked upby the central processor unit
(CPU) and used by the CPU logic to act upon the stored equation in
ROM to produce an output for the driver circuits. In known fashion,
the processor monitors the sensor information during successive
control loops as it performs sequentially the process steps.
[0007] The interior heat content for an automotive vehicle is
affected by a number of variables including but not limited to the
sun load heat flux (kW/m.sup.2), the effective glass area capable
of transmitting a solar heat load, the heat generated by passengers
and electronic devices within the vehicle passenger compartment,
the ambient temperature of the air surrounding the vehicle, the
mass air flow rate (enthalpy rate per degree), the average outlet
temperature of the air conditioning system, and the heat transfer
coefficient for heat transfer between the passenger compartment and
the ambient air. An automotive temperature control system should
take the thermodynamic interaction of these variables into account
in an attempt to maintain a target interior temperature in the most
effective way.
[0008] U.S. Pat. No. 5,832,990, which was awarded to the present
inventor, is an example of an automatic climate control system for
vehicles that respond to the above mentioned variables, including
airflow. The '990 patent teaches an automatic interior temperature
control system for an automotive vehicle capable of controlling
heat flux in response to changes in (but not limited to) ambient
temperature, outlet temperature, sun load and air flow by taking
into account the relationship between these four variables in
accordance with thermodynamic principles wherein an adjustment in
heat flux corrects an interior temperature error. U.S. Pat. Nos.
6,272,871 and 6,272,873 are examples of prior art air conditioning
systems, the content of which is incorporated herein by
reference.
SUMMARY OF THE INVENTION
[0009] There is a desire to automatically control the temperature
in two zones inside a vehicle while an adjustment in heat flux
corrects an interior temperature error. Some climate control
algorithms calculate two separate outlet temperatures that are
based on empirically determined factors or gains applied to various
sensor inputs that depend on expensive trial and error vehicle
level testing. These algorithms do not take into account heat flow
considerations, or at best minimize the heat flow considerations
due to the absence of the direct influence of system airflow in the
calculation method. This omission creates error and considerable
compromise in the task of achieving an appropriate climate for each
zone, particularly when the target zone temperatures differ.
[0010] This is a problem because in a typical operating
environment, for example, either more or less cooling is required
depending upon whether the vehicle is unshaded or shaded. The
previous dual zone climate control systems attempt to adjust the
outlet temperatures to achieve a target interior temperature
without taking into account the effect of air flow in the control
of total heat load. They are designed to affect adjustment in the
temperature of the system outlet, but they do not provide a
quantifiable and significant change in the total heat flux itself
as the system attempts to achieve a target interior
temperature.
[0011] The present inventor has discovered a dual zone automatic
climate control algorithm utilizing a heat flux analysis that
overcomes the deficiencies in the prior art. The present inventor
has discovered a set of control equations for a dual zone (by way
of example and not by limitation: left-right) using energy balance
considerations for the thermal influence in the vehicle cabin. The
factor of airflow is included directly in the calculations of the
two outlet temperatures. This considerably simplifies the
development process and often inherently corrects errors that are
generated by neglecting the direct influence of airflow. A logic
system utilizing the equations addresses thermal balance of two
zones that may have a single interior temperature sensor (for low
cost reasons) to ones with multiple interior sensors. Further, the
present invention can provide for a single airflow source for the
system, but is not limited to such a design. In such a scenario, a
primary zone and a secondary zone is defined for the purpose of
control priority. The primary zone can be used to govern the
transient (overall cabin temperature correction) and set up the
total system airflow. The secondary zone can be provided with a
stabilization enhancement logic that may provide increases to the
system airflow, only when the full cold or full hot outlet
temperatures are not sufficient for that zone's temperature
achievement. In addition, the secondary zone can be provided with
transient enhancement logic, which creates a temporary outlet
temperature overshoot that depends on the rate of this zone's
temperature target adjustment.
[0012] In one embodiment of the present invention, there is a
method for automatically controlling the climate in a plurality of
climate control zones of a cabin of an automobile comprising at
least a first zone and a second zone having a temperature sensor
located in the first zone and a conditioned air outlet vent in each
of the zones, the method comprising, obtaining a target temperature
value for the first zone and the second zone; obtaining a first
zone temperature value estimate from the sensor in the first zone;
obtaining an ambient air temperature value; obtaining a sun load
heat flux value for at least one of the first zone and the second
zone; obtaining a first zone gain factor value based at least on
the first zone temperature value estimate; automatically
determining the outlet temperatures and the mass flow rates of the
first zone outlet and the second zone outlet based at least on the
above obtained values and on a conduction/convection heat transfer
coefficient between the cabin and the ambient air, an effective
glass area for solar load transmission, a zone air crossover
influence factor, and predetermined constraints on the relationship
of the outlet temperatures and air flow, wherein the zone air
crossover influence factor is a factor based on blending of the air
in the cabin; and providing conditioned air to the cabin from the
first zone outlet and the second zone outlet at outlet temperatures
and mass flow rates correlating to the determined outlet
temperatures and mass flow rates.
[0013] In another embodiment of the present invention there is a
method wherein the zone air crossover influence factor is variable
and depends on an air distribution mode.
[0014] In another embodiment of the present invention the method
further includes calculating an error term and subtracting it from
the second zone outlet temperature to establish a new second zone
outlet temperature, the error term comprising a value based on the
first zone target temperature value, the first zone temperature
value estimate, the mass air flow rate of the second zone outlet,
and a second zone gain factor value based at least on the first
zone temperature value estimate, wherein the conditioned air
provided to the second zone is at the new second zone outlet
temperature.
[0015] In another embodiment of the present invention, there is a
method wherein the first zone gain factor value and the second zone
gain factor value are approximately equal when the first zone
temperature estimate is between about 20.degree. C. and about
28.degree. C.
[0016] In another embodiment of the present invention, there is a
method wherein the first zone gain factor value and the second zone
gain factor value vary inversely in relation to changing first zone
temperature estimates between at least the range from about
10.degree. C. to about 20.degree. C. and between at least the range
from about 28.degree. C. to about 35.degree. C.
[0017] In another embodiment of the present invention, there is a
method wherein the first zone gain factor value decreases with
increasing first zone temperature estimates below about 20.degree.
C. and increases with increasing first zone temperature estimates
above about 28.degree. C.
[0018] In another embodiment of the present invention, the method
further includes calculating an overset value to be added to the
second zone outlet temperature value, the overset value comprising
a value based on the second zone target temperature value, the
conduction/convection heat transfer coefficient between the cabin
and the ambient air, and the mass air flow rate, as adjusted by a
value that sets the strength of the overshoot.
[0019] In another embodiment of the present invention, there is a
method wherein the mass flow rate of the conditioned air provided
to the first zone is about the same as the mass flow rate of the
conditioned air provided to the second zone.
[0020] In another embodiment of the present invention, the method
that further includes calculating a minimum mass air flow rate
based on the conduction/convection heat transfer coefficient
between the cabin and the ambient air, the second zone target
temperature value, the ambient air temperature value, the sun load
heat flux value for the second zone, the effective glass area for
solar load transmission, and a capacity temperature value selected
from a group consisting of a constant cooling device temperature
and a constant heating device temperature, and wherein the mass air
flow rate of the conditioned air delivered to the cabin is based on
the calculated minimum mass air flow rate.
[0021] In another embodiment of the present invention, there is a
method wherein the mass air flow rate of the air delivered to the
cabin is limited to a predetermined maximum mass air flow rate
above a variable mass flow rate based on predetermined
constraints.
[0022] In another embodiment of the present invention, the variable
mass flow rate is based on predetermined constraints is
substantially correlated to various blower voltages, the maximum
mass air flow rate is substantially correlated to the blower
voltage, and wherein the maximum mass air flow rate is limited to
an equivalent blower voltage that is no greater than about 2 volts
above the equivalent voltage of the mass air flow rate based on
predetermined constraints.
[0023] In another embodiment of the present invention, there is a
method wherein the conditioned air provided to the cabin from the
first zone outlet and the second zone outlet at outlet temperatures
and mass flow rates is equal to the determined outlet temperatures
and mass flow rates, respectively.
[0024] In another embodiment of the present invention, there is a
method for automatically controlling the climate in a plurality of
climate control zones of a cabin of an automobile comprising at
least a first zone and a second zone having a temperature sensor
located in a first zone and an conditioned air outlet vent in each
of the zones, the method comprising at least utilizing an algorithm
relating to at least the equations
ToD=[TGT(D)+(Ge.multidot.(TGT(D)-RMd)+K.multidot.(TGT(D)-T.sub.a)-q.sub.s(-
D).multidot.GL)/GA-R.multidot.ToPa]/(1-R)
and
ToP=ToD+([TGT(P)-TGT(D)].multidot.(1+K/GA)-[q.sub.s(P)-q.sub.s(D)].multido-
t.GL/GA)/(1-R)
[0025] where:
[0026] ToD=First zone outlet temperature,
[0027] ToP=Second zone outlet temperature,
[0028] TGT(D)=First zone target temperature,
[0029] TGT(P)=Second zone target temperature,
[0030] Ge=Gain factor,
[0031] RMd=First zone temperature estimate from sensor,
[0032] q.sub.s(D)=First zone sun load heat flux,
[0033] q.sub.s(P)=Second zone sun load heat flux,
[0034] GL=Effective glass area for solar load transmission,
[0035] T.sub.a=Ambient temperature,
[0036] GA=Mass air flow rate,
[0037] K=Conduction or convection heat transfer coefficient between
the cabin and the ambient air,
[0038] R=Zone crossover influence factor,
[0039] ToPa=The second zone's true outlet temperature, (Evaporator
Temperature.ltoreq.ToPa.ltoreq.Heater Air Outlet Temperature,
[0040] the method comprising, automatically determining ToD, ToP,
and GA by solving the above equations with predetermined
constraints on the relationship of ToD, ToP, and GA; and providing
conditioned air to the cabin from the first zone outlet and the
second zone outlet at outlet temperatures and mass flow rates
correlating to the determined outlet temperatures and mass flow
rates.
[0041] In another embodiment of the present invention, there is a
method wherein
Ge'.multidot.(TGT(D)-RMd)/GA
[0042] is subtracted from the calculated value of ToP, wherein Ge'
is a gain factor less than or equal to Ge.
[0043] In another embodiment of the present invention, there is a
method wherein Ge and Ge' are approximately equal when the first
zone temperature estimate is between about 20.degree. C. and about
28.degree. C.
[0044] In another embodiment of the present invention, there is a
method wherein Ge and Ge' vary inversely in relation to changing
first zone temperature estimates between at least the range from
about 10.degree. C. to about 20.degree. C. and between at least the
range from about 28.degree. C. to about 35.degree. C.
[0045] In another embodiment of the present invention, there is a
method wherein Ge decreases with increasing first zone temperature
estimates below about 20.degree. C. and increases with increasing
first zone temperature estimates above about 28.degree. C.
[0046] In another embodiment of the present invention, there is a
method wherein
OverSet.multidot.[1+K/GA]
[0047] is added to the value of ToP, where
OverSet=X.multidot.(TGT(P)-FSet),
[0048] where X is a calibration value, and where
FSet=FSet+Y.multidot.(TGT(P)-FSet),
[0049] where Y is a multiplier that is arbitrarily set to allow the
FSet equation to be utilized in an algorithm that obtains the unity
value of FSet by a loop routine.
[0050] In another embodiment of the present invention, the method
further includes calculating a minimum mass air flow rate from the
equation:
GA=K.multidot.(TGT(P)-Ta-q.sub.s(P).multidot.GL/K)/(Capacity
Temperature-TGT(P))
[0051] where Capacity Temperature is a value selected from a group
consisting of a constant cooling device temperature and a constant
heating device temperature, and wherein the mass air flow rate of
the conditioned air delivered to the cabin is based on the
calculated minimum mass air flow rate.
[0052] In another embodiment of the present invention, there is a
method wherein the mass air flow rate of the air delivered to the
cabin is limited to a predetermined maximum mass air flow rate
above a variable mass flow rate based on predetermined
constraints.
[0053] In another embodiment of the present invention, there is a
method wherein the variable mass flow rate based on predetermined
constraints is substantially correlated to various blower voltages,
the maximum mass air flow rate is substantially correlated to the
blower voltage, and wherein the maximum mass air flow rate is
limited to an equivalent blower voltage that is no greater than
about 2 volts above the equivalent voltage of the mass air flow
rate based on predetermined constraints.
[0054] In another embodiment of the present invention, there is a
method wherein the constraints include human constraint factors
that modify thermodynamic constraint factors in the relationship of
air flow and the outlet temperatures, and wherein the method
further includes repeatedly addressing the constraints in response
to incremental changes in variables in the equations to effect a
change that will result in a modification of the outlet
temperatures.
[0055] In another embodiment of the present invention, there is a
method wherein the conditioned air provided to the cabin from the
first zone outlet and the second zone outlet at outlet temperatures
and mass flow rates is equal to the determined outlet temperatures
and mass flow rates, respectively.
[0056] In another embodiment of the present invention, there is an
automatic climate control apparatus for automatically controlling
the climate in a plurality of climate control zones of a cabin of
an automobile comprising at least a first zone and a second zone,
comprising, an air blower adapted to blow conditioned air into the
cabin; an air outlet vent in the first zone in fluid communication
with the air blower; an air outlet vent in the second zone in fluid
communication with the air blower; an air cooling device and an air
heating device in fluid communication with the air blower, the
first zone vent, and the second zone vent; a temperature sensor
located in the first zone adapted to provide a temperature value
estimate of the first zone; an electronic processor device
comprising a processor and a memory, wherein the memory is adapted
to store a plurality of equations, the plurality of equations
including equations for the air outlet temperatures and mass flow
rates of the first zone outlet and the second zone outlet, the
equations being based on variables including, a target temperature
value for the first zone and the second zone; a first zone
temperature value estimate; an ambient air temperature value; a sun
load heat flux value for at least one of the first zone and the
second zone; a first zone gain factor value based at least on the
first zone temperature value estimate; a conduction/convection heat
transfer coefficient between the cabin and the ambient air; an
effective glass area for solar load transmission; and a zone air
crossover influence factor, wherein the zone air crossover
influence factor is a factor based on the blending of the air in
the cabin; wherein the electronic processor is adapted to
automatically control and adjust the mass flow rate and the
temperature of the air being blown from the vents based on the
equations as constrained by predetermined constraints on the
relationship of the outlet temperatures and air flow.
[0057] In another embodiment of the present invention, the
apparatus includes a device adapted to vary the amount of air
entering the cabin that has passed through or around the air
heating device.
[0058] In another embodiment of the present invention, the
apparatus includes an automobile having an automatic climate
control system.
[0059] In another embodiment of the present invention, the
apparatus is adapted so that the conditioned air provided to the
cabin from the first zone outlet and the second zone outlet at
outlet temperatures and mass flow rates is equal to the determined
outlet temperatures and mass flow rates, respectively.
[0060] In another embodiment of the present invention, there is a
device for controlling at least one component of a climate control
system that controls the climate in a plurality of climate control
zones of a cabin of an automobile comprising at least a first zone
and a second zone, comprising, a device adapted to receive a signal
representing the mass flow rate of conditioned air being blown into
the cabin; a device adapted to output a signal to control the
heating and cooling of air being blown into the cabin; a device
adapted to output a signal to control the mass flow rate of air
being blown into the cabin; a device adapted to receive a signal
representative of a sensed temperature inside the cabin; a device
storing an algorithm based on at least a plurality of equations,
the plurality of equations including equations for air outlet
temperatures and mass flow rates of first zone outlet and second
zone outlet, the equations being based on variables including, a
target temperature value for the first zone and the second zone; a
first zone temperature value estimate; an ambient air temperature
value; a sun load heat flux value for at least one of the first
zone and the second zone; a first zone gain factor value based at
least on the first zone temperature value estimate; a
conduction/convection heat transfer coefficient between the cabin
and the ambient air; an effective glass area for solar load
transmission; and a zone air crossover influence factor, wherein
the zone air crossover influence factor is a factor based on the
blending of the air in the cabin; and a device storing a plurality
of predetermined constraints on the relationship of the first zone
and second zone outlet temperatures and air flow; wherein the
control device is adapted to automatically output a signal to
control and adjust the mass flow rate and the temperature of the
air being blown from the vents based on the equations as
constrained by the predetermined constraints on the relationship of
the outlet temperatures and air flows.
[0061] In another embodiment of the present invention, there is a
method for automatically controlling the climate in a plurality of
climate control zones of a cabin of an automobile comprising at
least a first zone and a second zone having a temperature sensor
located in the first zone and a temperature sensor located in the
second zone and an conditioned air outlet vent in each of the
zones, the method comprising, obtaining a target temperature value
for the first zone and the second zone; obtaining temperature value
estimates for the first zone and the second zone from the first
zone temperature sensor and the second zone temperature sensor
respectively; obtaining an ambient air temperature value; obtaining
a sun load heat flux value for at least one of the first zone and
the second zone; obtaining at least one of a gain factor value
based the first zone temperature value estimate and a gain factor
value based on the second zone temperature value estimate;
automatically determining the outlet temperatures and the mass flow
rates of the first zone outlet and the second zone outlet based at
least on the above obtained values and on a conduction/convection
heat transfer coefficient between the cabin and the ambient air, an
effective glass area for solar load transmission, a zone air
crossover influence factor, and predetermined constraints on the
relationship of the outlet temperatures and air flow; wherein the
zone air crossover influence factor is a factor based on the
blending of the air in the cabin; and, providing conditioned air to
the cabin from the first zone outlet and the second zone outlet at
outlet temperatures and mass flow rates correlating to the
determined outlet temperatures and mass flow rates.
[0062] In another embodiment of the present invention, there is a
method wherein the zone air crossover influence factor is variable
and depends on an air distribution mode.
[0063] In another embodiment of the present invention, there is a
method wherein the mass flow rate of the conditioned air provided
to the first zone is about the same as the mass flow rate of the
conditioned air provided to the second zone.
[0064] In another embodiment of the present invention, the method
further includes calculating a minimum mass air flow rate based on
the conduction/convection heat transfer coefficient between the
cabin and the ambient air, the second zone target temperature
value, the ambient air temperature value, the sun load heat flux
value for the second zone, the effective glass area for solar load
transmission, and a capacity temperature value selected from a
group consisting of a constant cooling device temperature and a
constant heating device temperature, wherein the mass air flow rate
of the conditioned air delivered to the cabin is based on the
calculated minimum mass air flow rate.
[0065] In another embodiment of the present invention, there is a
method wherein the mass air flow rate of the air delivered to the
cabin is limited to a predetermined maximum mass air flow rate
above a variable mass flow rate based on predetermined
constraints.
[0066] In another embodiment of the present invention, there is a
method wherein the variable mass flow rate based on predetermined
constraints is substantially correlated to various blower voltages,
the maximum mass air flow rate is substantially correlated to the
blower voltage, and wherein the maximum mass air flow rate is
limited to an equivalent blower voltage that is no greater than
about 2 volts above the equivalent voltage of the mass air flow
rate based on predetermined constraints.
[0067] In another embodiment of the present invention, there is a
method wherein the conditioned air provided to the cabin from the
first zone outlet and the second zone outlet at outlet temperatures
and mass flow rates is equal to the determined outlet temperatures
and mass flow rates, respectively.
[0068] In another embodiment of the present invention, there is a
method for automatically controlling the climate in a plurality of
climate control zones of a cabin of an automobile comprising at
least a first zone and a second zone and having a temperature
sensor located in the first zone and a temperature sensor located
in the second zone and an air outlet vent in each of the zones, the
method comprising at least utilizing an algorithm relating to at
least the equations:
ToD=[TGT(D)+(Ge.sub.(D).multidot.(TGT(D)-RMd)+K.multidot.(TGT(D)-T.sub.a)--
q.sub.s(D).multidot.GL)/GA.sub.(D)-R.multidot.ToPa]/(1-R)
[0069] and
ToP=[TGT(P)+(Ge.sub.(P).multidot.(TGT(P)-RM.sub.p)+K.multidot.(TGT(P)-T.su-
b.a)-q.sub.s(P)-R.multidot.ToDa]/(1-R)
[0070] where:
[0071] ToD=First zone outlet temperature,
[0072] ToP=Second zone outlet temperature,
[0073] TGT(D)=First zone target temperature,
[0074] TGT(P)=Second zone target temperature,
[0075] Ge.sub.(D)=Gain factor based on a first zone temperature
value estimate,
[0076] Ge.sub.(P)=Gain factor based on a second zone temperature
value estimate,
[0077] RMd=First zone temperature estimate from sensor,
[0078] RMp=Second zone temperature estimate from sensor,
[0079] q.sub.s(D)=First zone sun load heat flux,
[0080] q.sub.s(P)=Second zone sun load heat flux,
[0081] GL=Effective glass area for solar load transmission,
[0082] T.sub.a=Ambient temperature,
[0083] GA.sub.(D)=Mass air flow rate of the first zone,
[0084] GA.sub.(p)=Mass air flow rate of the second zone,
[0085] K=Conduction or convection heat transfer coefficient between
the cabin and the ambient air,
[0086] R=Zone crossover influence factor,
[0087] ToPa=The second zone's true outlet temperature, (Evaporator
Temperature.ltoreq.ToPa.ltoreq.Heater Air Outlet Temperature,
[0088] ToDa=The first zone's true outlet temperature, (Evaporator
Temperature.ltoreq.ToDa.ltoreq.Heater Air Outlet Temperature,
[0089] the method comprising:
[0090] automatically determining ToD and ToP, and GA by solving the
above equations with predetermined constraints on the relationship
of ToD, ToP, GA.sub.(D) and GA.sub.(P); and
[0091] providing conditioned air to the cabin from the first zone
outlet and the second zone outlet at outlet temperatures and mass
flow rates correlating to the determined outlet temperatures and
mass flow rates.
[0092] In another embodiment of the present invention, there is a
method wherein the conditioned air provided to the cabin from the
first zone outlet and the second zone outlet at outlet temperatures
and mass flow rates is equal to the determined outlet temperatures
and mass flow rates, respectively.
[0093] In another embodiment of the present invention, there is a
method wherein GA.sub.(D) is equal to or about equal to
GA.sub.(P).
[0094] In another embodiment of the present invention, there is a
method wherein Ge.sub.(D) is equal to or about equal to
Ge.sub.(P).
[0095] In another embodiment of the present invention, the method
further includes calculating a minimum mass air flow rate from the
equation:
GA.sub.(D/p)=K.multidot.(TGT(P)-Ta-q.sub.s(P).multidot.GL/K)/(Capacity
Temperature-TGT(P))
[0096] where Capacity Temperature is a value selected from a group
consisting of a constant cooling device temperature and a constant
heating device temperature, and wherein the mass air flow rate of
the conditioned air delivered to the cabin is based on the
calculated minimum mass air flow rate.
[0097] In another embodiment of the present invention, there is a
method wherein the mass air flow rate of the air delivered to the
cabin is limited to a predetermined maximum mass air flow rate
above a variable mass flow rate based on predetermined
constraints.
[0098] In another embodiment of the present invention, there is a
method wherein the variable mass flow rate based on predetermined
constraints is substantially correlated to various blower voltages,
the maximum mass air flow rate is substantially correlated to the
blower voltage, and wherein the maximum mass air flow rate is
limited to an equivalent blower voltage that is no greater than
about 2 volts above the equivalent voltage of the mass air flow
rate based on predetermined constraints.
[0099] In another embodiment of the present invention, there is an
automatic climate control apparatus for automatically controlling
the climate in a plurality of climate control zones of a cabin of
an automobile comprising at least a first zone and a second zone,
comprising: an air blower adapted to blow conditioned air into the
cabin; an air outlet vent in the first zone in fluid communication
with the air blower; an air outlet vent in the second zone in fluid
communication with the air blower; an air cooling device and an air
heating device in fluid communication with the air blower, the
first zone vent, and the second zone vent; a temperature sensor
located in the first zone adapted to provide a temperature value
estimate of the first zone; an electronic processor device
comprising a processor and a memory, wherein the memory is adapted
to store a plurality of equations, the plurality of equations
including equations for the air outlet temperatures and mass flow
rates of the first zone outlet and the second zone outlet, the
equations being based on variables including: a target temperature
value for the first zone and the second zone; a first zone
temperature value estimate; an ambient air temperature value; a sun
load heat flux value for at least one of the first zone and the
second zone; a first zone gain factor value based at least on the
first zone temperature value estimate; a conduction/convection heat
transfer coefficient between the cabin and the ambient air; an
effective glass area for solar load transmission; and a zone air
crossover influence factor, wherein the zone air crossover
influence factor is a factor based on the blending of the air in
the cabin; wherein the electronic processor is adapted to
automatically control and adjust the mass flow rate and the
temperature of the air being blown from the vents based on the
equations as constrained by predetermined constraints on the
relationship of the outlet temperatures and air flow.
[0100] In another embodiment of the present invention, there is a
method wherein the first zone is a driver zone and the second zone
is the passenger zone.
[0101] In another embodiment of the present invention, there is an
apparatus wherein the first zone is a driver zone and the second
zone is the passenger zone.
BRIEF DESCRIPTION OF THE DRAWINGS
[0102] These and other features, aspects, and advantages of the
present invention will become more apparent from the following
description, appended claims, and accompanying exemplary
embodiments shown in the drawings, which are briefly described
below.
[0103] FIG. 1 schematically illustrates an overall vehicle
installation of a climate control system of the prior art which can
be adapted for practice with the present invention.
[0104] FIG. 2 schematically illustrates the stabilized condition
that is obtained when air flow changes as the target cabin
temperature is maintained during calibration of the system.
[0105] FIG. 3 schematically illustrates a dual zone cabin.
[0106] FIG. 4 schematically shows generalized energy balance
constraints for a climate control system and an empirical
relationship that indicates constraints imposed by human
factors.
[0107] FIG. 5 schematically illustrates an example of error gain
factor values.
[0108] FIG. 6 is a logic flow chart illustrating process steps to
implement an embodiment of the present invention.
[0109] FIG. 7 is a logic flow chart illustrating process steps to
implement an embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0110] The climate control system of the present invention for the
cabin of an automobile (such as but not limited to a car, an SUV, a
minivan, a station wagon, a pickup truck, etc.) allows an occupant
or a plurality of occupants to select the desired temperature to be
maintained inside the cabin. For example, the present invention can
permit the driver to identify a cabin temperature value (e.g.
72.degree. F.) that the driver finds comfortable, and the climate
control system of the automobile adjusts various components of the
system to maintain or at least strive to achieve the set
temperature (target temperature), in at least the driver side of
the cabin, while maintaining or striving to maintain a separate
temperature or the same temperature in another part of the cabin.
Climate control systems include but are not limited to systems that
utilize air conditioning systems and heater systems. However, it is
noted that the present invention can be used for any system that
has an effect on cabin temperature. The present invention can be
utilized with a climate control system of the prior art as seen in
FIG. 1 and described above, with modifications to the system for a
dual zone climate control system. For exampleFor example, there
could be a separate blend door (or mix door) for the driver zone
and a separate door for the passenger zone to vary the outlet
temperature of the air being blown into the respective zones of the
cabin. Further by way of example and not by way of limitation,
there could be a separate heat transfer device 327 for the driver
zone and the passenger zone, which could include by way of example,
a separate evaporator and heater core. Further by way of example
and not by limitation, other configurations could include separate
heater cores, evaporator cores, blowers and combinations of single
and dual components. Further, heat exchangers that limit internal
fluid flow, as opposed to diverting airflow, may be applied.
[0111] The desired temperature, set by the driver for example, is
the target temperature or stabilized or cabin average temperature
of the cabin of the automobile. The temperature of the cabin is
determined by a single sensor or a plurality of sensors that are
located in the cabin of the automobile. During design of the
automobile, the placement of the sensor/sensors tends to vary
depending on the model of the automobile. For example, in the case
of a single sensor, designers sometimes place the sensor on the
dash board or on the ceiling of the automobile or on a center
console of the automobile. Typically, the sensor location is
determined based on manufacturing constraints or aesthetic design
constraints of the interior of the automobile. For example, a
sensor that is located on the dash board exactly in the center of
the automobile may be aesthetically unpleasing to a prospective
buyer of the automobile. Thus, it is often the case that the
temperature sensor is located in places where less than accurate
reading will be produced, or the sensor is placed in a location
where the temperature sensed by the sensor lags the actual
temperature or the temperature perceived by the vehicle occupants.
For example, if the sensor is placed underneath the seat and
conditioned air is being blown into the cabin through vents in the
top of the dashboard, and the target temperature was changed, the
occupants of the car would sense a change in the temperature
significantly prior in time to the sensor underneath the seat
sensing the change. To remedy this, empirical testing is performed
in the cabin of a given automobile class, such as by way of example
and not by way of limitation, a Nissan Xterra, to determine the
error that is present in a system after a change in target
temperature. Through extensive empirical testing that optionally
takes into account human factor constraints, an error gain function
can be determined to compensate for the discrepancy between the
sensed temperature and the target temperature. Thus, through
empirical testing, a gain function can be obtained for a given
automobile class to provide a highly satisfactorily automobile
climate control system for a user. It is noted that the empirical
testing would probably be necessarily performed for each different
class of car. Thus, for example, empirical testing results for the
Nissan Xterra may not be applicable for a Nissan Maxima; thus,
empirical testing will probably be necessary for the Maxima.
However, it is possible that the present invention can be practiced
by using the same or similar results from one class of car for
another class of car thus eliminating or reducing the empirical
testing necessity.
[0112] The control systems of the present invention can include but
is not limited to a series of vents that channel or expel
conditioned air into an automobile cabin. (It is noted that
conditioned air includes but is not limited to both cool air which
would be obtained, by way of example only and not by way of
limitation, from an air conditioning system, and heated air which,
for example, would be obtained by passing air through or over a
heater core, and would also include air at the ambient temperature
as well.) These vents can have vent outlets that are located in a
variety of locations in the cabin. For example, automobiles often
have vent outlets on the top of the dashboard, in the dashboard
roughly at the level of the user's chest, and below the dashboard
roughly at the level of the user's knees or on the floor. The vent
outlets are also sometimes located in door panels, in ceilings and
in the rear of the cabin as well. The present invention can be
practiced with vent outlets anywhere in the cabin.
[0113] The primary method of altering or maintaining the climate in
the cabin of an automobile in the preferred embodiment of the
present invention is by varying or maintaining an outlet
temperature of the conditioned air blown into the cabin, where
outlet temperature can be defined as, by way of example only but
not by way of limitation, the temperature of the air as measured at
the vent outlet(s). A second method of varying or controlling the
climate in the cabin of an automobile is by varying the velocity,
or more appropriately, the mass flow, of the conditioned air being
blown into the cabin. This can be accomplished, for example, by
adjusting the voltage of the electrical current being supplied to
an electric motor connected to a fan. Thus, for example, by
increasing the blower voltage, the velocity or mass flow of the air
being blown from the vent would increase. Further by way of
example, by decreasing the voltage, the velocity or mass flow rate
of the air being blown into the cabin would be reduced.
[0114] For economic reasons, the automobile climate control system
of the preferred embodiment of the present invention primarily
operates with a blower that moves air in about the same quantity
throughout the cabin. That is, by way of example, the quantity of
the air being blown out the outlet on the driver's side of the
automobile is the same or approximately the same amount of air
being blown out the outlet on the passenger's side of the
automobile. It is noted that the present inventor recognizes that
minor differences in mass flow rate between the zones are almost
always present in a climate control system. By way of example and
not by way of limitation, in the case of a plurality of blowers,
one blower may operate to move a higher quantity of air, due to,
say, manufacturing tolerances, than another, even though they are
set at the same speed (to deliver the same quantity of air).
Further by way of example and not by limitation, the air flow
passages to the zones can be configured differently, and there can
be obstructions or a greater degree of obstruction in the air flow
to the zones (this could be the case in the situation where the
driver zone mix door is positioned to direct more air around the
heater core than the passenger zone mix door). However, it is noted
that in certain cases, as will be seen below, this blower speed is
different from one side of the car to the other. Further, it is
noted that the present invention can be practiced in a system where
the mass flow rate of the air being blown out the outlets on the
driver's side is different from that of the passenger's side. Such
a situation would be present in the case of a system utilizing
independently controlled blowers, so that the blower(s) of the
driver zone would intentionally operate at a speed different than
those of the passenger zone.
[0115] The present invention provides a climate control system for
an automobile that operates by varying the outlet temperature of
the air being blown into the cabin. The value of this outlet
temperature is based on a variety of functions. That is, the outlet
temperature of a preferred embodiment of the present invention is
not simply the target temperature. Instead, the outlet temperature
of the present invention is a temperature that will produce a
sensed interior temperature, and is a function of, by way of
example and not by way of limitation, the ambient temperature, the
sun load, and air flow. Thus, the outlet temperature is often a
dynamic temperature that varies in response to varying conditions
in response to varying functions to achieve or maintain a desired
target temperature. In addition, the outlet temperature is dynamic
to meet the driver's and passenger's expectations. That is, their
expectations as to what the climate inside the automobile should
feel like is taken into account. Thus, the outlet temperature is
further influenced by predetermined human factor constraints.
[0116] It is noted that the outlet temperature can be both an
instantaneous temperature as well as an average temperature,
depending on the types of sensors utilized to determine the
temperature. It is further noted that it is not necessary to
measure the outlet temperature in real time, as empirical testing
can be performed to obtain accurate estimates of the outlet
temperature for a given setting. By way of example and not by way
of limitation, an outlet temperature can be estimated based on
empirical testing at a given blend door position based on the
evaporator temperature and the heater core temperature, the
combination of the two creating the outlet temperature. This
information can be stored in an onboard computer, and thus looked
up. Thus, the outlet temperatures can be substituted with variables
representing the position or setting of one or more of the
components used to vary the outlet temperature in the
automobile.
[0117] The control equation taught in the '990 patent provides a
teaching of an algorithm to calculate the average outlet
temperature of the air leaving the outlet of the air vents of a
climate control system. The control equation is a suitable
foundation for the present invention because it inherently manages
interior temperature without the necessity for making complex and
tedious gain adjustments, and is derived from the stabilized
interior temperature of an automobile. The equation for the outlet
temperature in a system embodying the teachings of the '990 patent
reacts to changes in air flow to keep the interior temperature at a
target value. By altering air flow, changes are made automatically
in the way that the heat control equation behaves. Thus, on a hot,
sunny day, if the air flow should be decreased, the outlet
temperature will become colder in order to keep the target interior
temperature at the desired level.
[0118] The '990 patent also teaches human factor constraints that
can be used in an automatic climate control system for an
automobile. These teachings are applicable to the present invention
and are incorporated herein in their entirety. A preferred
embodiment of the present invention utilizes some or all of the
human factor constraints taught in the '990 patent.
[0119] In conjunction with the teachings of the '990 patent, it is
seen that in a climate control system for a vehicle, where the
cabin heat flux (e.g. energy vs. time, with or without a direction
component) relationship is constant, the stabilized energy balance
relationship for the vehicle cabin can be expressed as follows:
0=GA.multidot.(TGT-T.sub.o)+K.multidot.(TGT-T.sub.a)-q.sub.s.multidot.GL
(1)
[0120] with,
[0121] T.sub.o=the average outlet temperature,
[0122] TGT=the stabilized room or cabin average temperature,
[0123] q.sub.s=the sun load heat flux,
[0124] GL=the effective glass area for solar load transmission,
[0125] T.sub.a=the ambient temperature (exterior),
[0126] GA=the mass air flow rate (enthalpy rate/degree),
[0127] K the conduction or convection heat transfer coefficient
(including area) between the room and ambient.
[0128] By solving equation (1) for T.sub.o, a basic climate control
equation for the stabilized condition that allows for the
calculation of the outlet temperature required to provide a given
target cabin temperature is as follows:
T.sub.o=target+(1/GA).multidot.[K.multidot.(target-T.sub.a).multidot.q.sub-
.s.multidot.GL] (2).
[0129] The above equation, plotted at 22 in FIG. 2, uses heat
transfer constants K and GL as the primary calibration values.
[0130] The interaction between air flow tuning and the interior
temperature is taken into account in a preferred embodiment in this
proportional control of the heat flux. It does this by combining
all of the variables automatically. Once adjustments are made to
the heat flow term, the heat flux relationship of the invention
accounts automatically for variations in all of the other factors.
Thus, the control equation used in practicing the invention
inherently manages interior temperature without the necessity for
making complex and tedious gain adjustments when airflow is not
present in the control equation.
[0131] The equation for the outlet temperature in a system
embodying the present invention will react to changes in air flow
to keep the interior temperature at a target value. By altering air
flow, changes are made automatically in the way that the heat
control equation behaves. Thus, on a hot, sunny day, for example,
if the air flow should be decreased, the outlet temperature will
become colder in order to keep the target interior temperature at
the desired level.
[0132] If the air flow is changed during calibration to produce the
divergence indicated at 24 in the plot of FIG. 2, the stabilized
room temperature condition will be maintained. This is indicated by
the intersection of line 22 with the target room temperature line
at point "A" and the corresponding intersection point after an air
flow calibration change, as shown at point "B".
[0133] In FIG. 2, the heat flux control equation plotted with the
heavy line 22 will intersect the 25 degree room temperature line at
an outlet temperature of about 42 degrees. The corresponding outlet
temperature following air flow adjustment is about 37 degrees, as
shown in FIG. 2.
[0134] It is noted that FIG. 2 shows a situation where no error
exists between the interior temperature and the target temperature.
That is, if the interior temperature equals the target temperature,
the outlet temperature is calculated directly from equation (2).
The impact of an error on equation (2) is discussed below.
[0135] For a condition with a different sun load and target
temperature, the change in the outlet temperature is calculated
by:
.DELTA.T.sub.o=.DELTA.TGT+.vertline.K-.DELTA.TGT-GL.multidot..DELTA.q.sub.-
s].multidot.(1/GA)
or
.DELTA.T.sub.o(.DELTA.TGT).multidot.(1+K/GA)-.DELTA.q.sub.s.multidot.(GL/G-
A) (3).
[0136] It is noted that equations (1)-(3) are applicable to single
zone climate control systems. In a single zone climate control, the
cabin is regarded as one mass of uniform temperature air.
Conditioned air at the same average outlet temperature is delivered
to both sides of the vehicle and there is little or no net heat
transfer between the zones. That is, the air is at approximately
the same temperature. Thus, the equation (2) is applicable to the
entire cabin or it can be applied to each zone in individual
equations bearing half the total system airflow (GA), half the
glass area (GL) and half the surface for conduction (K). It is
noted that halving will arithmetically cancel and the outlet
temperature of equation 2 is not affected by this
conceptualization.
[0137] In a traditional vehicle climate control system, the
conditioned air delivered to the cabin is the same air delivered on
both sides of the cabin. That is, by way of example, a vent in the
driver's zone of the cabin nearest to the door would output air
having an outlet temperature the same as or about the same as a
vent on the passenger's zone of the cabin that is nearest to the
passenger's door. Further by way of example, this would be the case
with a vent positioned near the center of the cabin but still in
the driver's zone and a vent positioned near to the center but in
the passenger's zone. This would also be the case in situations
where, say, there are more vents on one side of the cabin than the
other side of the cabin, or in the case where the vents are not
evenly spaced (by way of example to accommodate a steering wheel or
a glove box) and/or situations where the vents are not evenly
spaced and more vents are located on one side of the compartment
than the other side of the compartment. In the dual zone climate
control system according to the present invention, it is possible
to deliver conditioned air at different outlet temperatures into
each zone.
[0138] Vehicle geometry can play a role in the extent of mixing
that will occur between the two zones, resulting in a crossover
influence. In a dual zone automobile climate control system the
outlet temperature of the conditioned air being blown from a vent
in the driver's zone could be different than the outlet temperature
of the conditioned air being blown from a vent in the passenger's
zone. Thus, in such a situation, the air on one side of the cabin
would be at a temperature that is different than the temperature of
the air on the other side of the cabin, thus providing the
capability of accommodating both the driver's and the passenger's
desires with respect to cabin climate. Air masses of different
temperatures have an effect on one another in regard to
temperature. That is, the air masses exert a cross over influence
on one or the other because the air is generally free to move from
one side of the cabin to the other. Indeed, in such situations, air
can be blown from one side of the cabin to the other. For example,
if a vent nearer to the center of the cabin but still in the
driver's zone is directed towards the passenger's zone of the
automobile, air at the outlet temperature of the driver's zone
would be blown into the passenger's side of the compartment. Still,
even in the case where, for example, air from the driver's zone
outlets is being blown away from the passenger's zone of the cabin
and in the case where air from the passenger's zone outlet is being
blown away from the driver's zone of the cabin, air will still
cross from one side of the cabin to the other. For example, this is
seen in the case of an automobile that has a center console which
often plays a prominent role in separating the air masses in the
case of air that is being blown out of floor vents. The larger in
general, or the higher (e.g. measured from the floor) specifically
the center console, less of a cross over influence will be present.
Further by way of example and not by limitation, seat geometry
plays a role, as well as ceiling geometry. Ceiling geometry, in the
case of, say, a center console attached to the roof which could
include lighting, a compass, temperature gauges, a video monitor,
etc., plays a role as well. In sum, air will move from one side of
the cabin to the other, and the amount of air is dependent on the
vehicle geometry which is generally fixed. FIG. 3 conceptually
shows the mixing that occurs between zones. The present invention
provides an algorithm to account for this phenomenon.
[0139] As noted above, the present invention utilizes the same
blower speed for both the driver and passenger zones of the
automobile. Thus, in determining the crossover influence of air
from one zone of the cabin to the other zone of the cabin, an
assumption can be made that the air flow into the two zones are
equal. As can be seen from the above discussion concerning cabin
interior geometry, this crossover effect will be variable depending
on the model of the automobile and indeed even perhaps some of the
selected additional features of the same model as well. Still, the
crossover influence can be determined through empirical testing of
a given automobile design. Thus, it is expedient to identify a
factor that can be inputted into equation (2) to account for the
crossover influence. It is noted that usually the crossover
influence, while almost always present, is often minimal.
Nonetheless, it is something that can be taken into account, as
will be seen below.
[0140] As with traditional climate control systems, a preferred
embodiment allows the driver to input a desired blower speed. For
example, the driver could be provided with, say, a four position
switch which, depending on what position is selected, would provide
a different blower speed, thus providing a different mass flow rate
into the cabin. In such a situation, the human factor constraints
used to constrain the control equations could be overridden based
on this inputted blower speed in the case where the blower speed is
different than the blower speed identified by the results of the
human factor tests. In such a situation, the control system would
then identify a new outlet temperature based on this new mass flow
rate. This outlet temperature would be calculated directly from the
control equations. Thus, in such a situation, the general value of
GA would be controlled by the user. It is noted that while the user
can have control over the blower speed by adjusting the setting on
the switch, the user may not have total control over the speed.
That is, he or she will have control over an approximate or general
blower speed, and the controller would make minor adjustments to
the blower speed, adjustments predetermined through empirical human
factor tests.
[0141] It is noted that while the terminology here utilizes the
phrases "driver zone" and "passenger zone," the phrases "first
zone" and "second zone" could be used respectively or visa-versa.
That is, the driver zone and the passenger zone simply represent
zones in the automobile, and are used here for convenience and
clarity.
[0142] As noted above, the mass flow rate of air being blown into
the cabin is the function of not only the blower speed, but also
the obstructions to the air being conditioned and blown into the
cabin. For example, in a scenario when the mix door is located at
the full closed position, there is less of an obstruction to the
airflow than when the door is placed on the full cold condition.
Thus, there is less of a pressure drop in the air flow channels in
the full cold position, and air will flow at a higher mass flow
rate into the cabin at the full cold position than the full hot
position even though the blower speed is the same in both
instances. It is noted that empirical testing can be performed on a
given model automobile to determine how the position of, for
example, the mix door changes the mass flow rate. Therefore, a
preferred embodiment of the present invention could also include a
controller that stores empirically determined mass flow rates based
on both varying blower speed as inputted by the driver as well as
varying obstructions in the airflow. These values could then be
utilized in the control equations for the mass flow rate.
[0143] For the sake of simplicity, it is assumed that the airflow
into the two zones are equal. Thus, the true average outlet
temperature into either zone will depend on an empirically
determined factor that is a blend of the outlet temperatures of the
vents in the driver's zone of the cabin (ToD) and the passenger's
zone of the cabin (ToP). The factor "R" is designed for this effect
and between 0 and 0.5, and generally but not always and certainly
not by limitation between 0.05 and 0.2, and often about 0.1.
Application of this factor in equation form in relation to the two
zones as seen in FIG. 3 results in:
Driver's True Average Outlet
Temp=(1.multidot.R).multidot.ToD+R.multidot.T- oP (4)
and
Passenger's True Average Outlet
Temp=(1-R).multidot.ToP+R.multidot.ToD (5).
[0144] The aim of the driver's side control equation (4) is to
calculate ToD, which may be altered to account for the passenger's
temperature influence. This is done by the following algebraic
steps that begin using equation (2) with the driver's target
temperature and sun load specified TGT(D) and qs(D)
respectively:
(1-R).multidot.ToD+R.multidot.ToP=TGT(D)+(1/GA).multidot.[K.multidot.(TGT(-
D)-T.sub.a)-q.sub.s(D).multidot.GL]
[0145] Thus,
ToD=[TGT(D)+(K/GA).multidot.(TGT(D)-T.sub.a)-q.sub.s(D).multidot.(GL/GA)-R-
.multidot.(ToP)]/(1-R).
[0146] As noted above, there is often an error associated with the
temperature sensed by a temperature sensor in the automobile. That
is, there is a difference between the target room temperature and
the actual cabin temperature, where the actual cabin temperature is
a temperature measured by the sensor. Through empirical testing
associated with a given vehicle design, an error term can be
identified that will provide a consistent heat flux gain for
proportional corrections. This error term can be added to equation
(4) along with a function based on the difference between the
drivers' zone room temperature estimate and the drivers' target
temperature. The error correction term uses the driver's zone room
temperature estimate (RMd) and an error gain (Ge). The equation
becomes:
ToD=[TGT(D)+(Ge.multidot.(TGT(D)-RMd)+K.multidot.(TGT(D).multidot.T.sub.a)-
-q.sub.s(D).multidot.GL)/GA-R.multidot.ToP]/(1-R)
[0147] However, through testing, it has been determined that a
value of ToP in the above equation should be constrained to a value
equal to or greater than the evaporator temperature but less than
or equal to the heater air outlet temperature. Thus, ToP is
substituted by a new variable, ToPa, and the above equation
becomes:
ToD=[TGT(D)+(Ge.multidot.(TGT(D)-RMd)+K(TGT(D)-T.sub.a)-q.sub.s(D).multido-
t.GL)/GA-R.multidot.ToPa]/(1-R) (6),
[0148] where
[0149] ToPa=The passenger zone's true outlet temperature,
(Evaporator Temperature.ltoreq.ToPa.ltoreq.Heater Air Outlet
Temperature.
[0150] It is noted that in the event that ToP falls within the
specified range (equal to or greater than the evaporator
temperature but less than or equal to the heater air outlet
temperature, ToPa=ToP.
[0151] A similar equation exists for the passenger's zone,
providing that a room temperature estimate is available for that
zone (RMp), which could be obtained, by way of example, from a
temperature sensor placed in the passenger zone. With subscript
changes for the passenger, this equation is:
ToP=[TGT(P)+(Ge.multidot.(TGT(P)-RMp)+K.multidot.(TGT(P).multidot.T.sub.a)-
-q.sub.s(P).multidot.GL)/GA-R.multidot.ToDa]/(1-R) (7),
[0152] where
[0153] ToDa The driver zone's true outlet temperature (Evaporator
Temperature.ltoreq.ToDa.ltoreq.Heater Air Outlet Temperature).
[0154] In an embodiment of the present invention having a plurality
of cabin temperature sensors, equations (6) and (7) can be solved
by iteration in a computer controller on board the automobile. The
value of R will depend on the air distribution mode (for example,
whether air is blowing from the floor vents, the dashboard vents,
or a combination of the two), and is determined through empirical
testing. In a preferred embodiment of the present invention, the
climate control system can be adapted to sense the air distribution
mode and to select the appropriate value of R. The value of Ge will
depend on the value of the room temperature estimates in order to
provide flexibility to the transient response calibration.
[0155] In a preferred embodiment of the present invention, the
computer controller periodically updates values for the above and
below equations with data that is obtained via real time
measurements or stored measurements, or both, and determines new
temperatures and mass flow rates. This is also done when the driver
or passenger changes his or her target temperature.
[0156] It is noted that a potential exists for values of one or
more of the variables of equations (6) and (7), as well as the
other equations presented herein, to be absent or not available. In
such a situation, a preferred embodiment of the invention can
utilize another variable or the last recorded value of the missing
variable. That is, if a variable must be obtained to utilize the
equations, the variable can be obtained by using a substitute. By
way of example and not by limitation, in a preferred embodiment of
the present invention, the automatic control system utilizes the
driver's zone target temperature for both the driver's zone and the
passenger zone until the passenger inputs a desired temperature.
Again by way of example and not by limitation, if the driver inputs
a target temperature of 72.degree. F. and the passenger does not
input a target temperature, the control system will use 72.degree.
F. for both the driver's side and the passenger zone equations.
Further by way of example, if the passenger later inputs a
temperature of, say, 75.degree. F. while the driver does not change
his or her temperature setting, the control system will utilize
75.degree. F. as the target temperature for the passenger and
72.degree. F. as the target temperature for the driver. As noted
above, the present invention can be practiced by utilizing such
logic not only for the target temperatures, but also for other
variables when a value is only available for one side of the
automobile. It is further noted that the values of Ge in equations
(6) and (7) can be equal to each other, as seen in the equations,
or equation (6) can have a value of Ge for the driver zone
temperature sensor and equation (7) can have a value of Ge for the
passenger zone temperature sensor.
[0157] It is further noted that the present invention can be
practiced by purposely canceling out some of the terms or
diminishing their impact on the equations. For example, the present
invention could be practiced by utilizing a value of Ge equal to 1.
Thus, equations (6) and (7) could be practiced by ignoring the gain
function.
[0158] Additionally, the present invention can be practiced by
utilizing the equations to determine an outlet temperature, and
then adding or subtracting a value or a series of values or
variable values from the determined outlet temperature, the
resulting temperature being used to set the actual outlet
temperature of the air being blown into the cabin. Thus, the outlet
temperatures and mass flow rates of conditioned air provided to the
cabin from at least one of the driver zone outlets and at least one
of the passenger zone outlets need only be correlated to the
determined outlet temperatures and mass flow rates, respectively.
However, in a preferred embodiment, a value equal to or about equal
to the outlet temperature determined from the equations is used to
set the actual outlet temperature.
[0159] The human factor constraints of a preferred embodiment of
the present invention will now be briefly discussed in an exemplary
manner. As can be seen from the control equations, outlet
temperature ToD and ToP is a function of a number of variables,
including the ambient temperature as well as the mass flow rate. In
one embodiment of the present invention, empirical testing is
performed to determine the most subjectively comfortable mass flow
rate and outlet temperature combinations to achieve a given
specified target temperature. For example, if a target temperature
is inputted as 70.degree. F. and the ambient temperature is
50.degree. F., there will be a variety of outlet temperatures and
mass flow rates that will meet the target temperature of the cabin.
However, there will be a more limited number of outlet temperatures
and mass flow rates that will be found to be comfortable to the
driver and/or the passenger and usually only one temperature and
one mass flow rate that is most comfortable to the driver or the
passenger. Thus, through empirical testing, this one most
comfortable temperature and mass flow rate can be determined. For
example, referring to FIG. 4, which shows an example of the
relationship of air flow and outlet temperature that is derived
from personal preferences and human factors, in the case where the
desired target temperature is 25.degree. C. and the ambient
temperature is 15.degree. C., empirical testing has shown for some
models of automobiles that an outlet temperature of approximately
43.degree. C. with an airflow rate, for example, of 40% of the
system's maximum capacity would be most comfortable. (Note that
this is just an example and empirical results may and probably will
vary.) Thus, it is seen that control equations for ToD and ToP can
be used with constraints based on empirical human factor results.
In the preferred embodiment of the present invention, these human
factor constraints are stored in a controller on board the
automobile and periodically looked up to constrain the control
equations. Thus, there is a predetermined relationship between the
outlet temperatures and the airflow.
[0160] A preferred embodiment of the present invention utilizes a
single sensor in the cabin which is located in the driver's zone.
This is done based on the presumption of the desirability of the
driver's zone temperature setting being dominant. That is, the
system reacts to the driver's zone temperature setting more than
the passenger's temperature setting. It is noted that the present
invention could be practiced utilizing passenger's side dominance
or some other form of dominance. However, since the preferred
embodiment relies on driver zone dominance, formulation of the
algorithm begins with a control equation for the driver's zone.
[0161] In this embodiment, the passenger does not have a room
temperature sensor available in the passenger zone. Because a
preferred embodiment of the present invention relies on driver's
side dominance, equation (6) can be used to formulate an algorithm
to practice the present invention. However, a new equation should
be identified as a control equation for the outlet temperature for
the passenger that utilizes the driver's zone sensor. This equation
is obtained by utilizing equation (3) as the basis for the
passenger's outlet temperature estimate in conjunction with
parameters from the driver's zone, as seen in the following
equation:
ToP-ToD=[TGT(P)-TGT(D)].multidot.(1+K/GA)-[q.sub.s(P)-q.sub.s(D)].multidot-
.GL/GA (8).
[0162] Substituting equation (5), the equation for the passenger's
true average outlet temperature, for ToP in equation (8)
yields:
(1-R).multidot.ToP+R.multidot.ToD-ToD=[TGT(A)-TGT(D)].multidot.(1+K/GA)-[q-
.sub.s(P)-q.sub.s(D)]GL/GA
[0163] or, solving for ToP:
ToP=ToD+([TGT(P)-TGT(D)].multidot.(1+K/GA)-[q.sub.s(P)-q.sub.s(D)].multido-
t.GL/GA)/(1-R) (9).
[0164] Thus, equation (9) above is a control equation of the outlet
temperature for the passenger in this embodiment of the present
invention of a driver's side dominant dual zone climate control
system.
[0165] In the preferred embodiment of an implementation of the
present invention, equations (6) and (9) are solved by iteration in
a computer controller on board the automobile. However, since
equation (9) does not contain an error correction term, as does
equation (6), the error correction (transient response) in this
embodiment of the present invention is dominated by the driver's
side control equation. While this is sometimes a neutral fact, and
sometimes even desirable, this fact can in some instances be
disruptive to the passenger's comfort when the driver is making
changes to the target temperature (TGT(D)) when the cabin
temperature is stable or nearly stable. In such situations, it is
convenient to subtract the error term from the value of ToP as
well. These situations have been determined through empirical
testing, and typically occur, but are not limited to, a perceived
"comfort zone" that spans from about 20.degree. C. to about
28.degree. C. It is noted that this zone is determined through
testing, and thus may be expanded or contracted or moved depending
on the results of the testing. Thus, other embodiments of the
present invention could have ranges that are wider or narrower in
whole or in part than the just mentioned range. Indeed, depending
on the results of the testing, the present invention could be
practiced by subtracting the error term from the value of ToP in a
comfort zone extending from below about 0.degree. C. to about
50.degree. C. and any range of temperatures in between in
0.1.degree. C. increments. Therefore, an equation for the passenger
side outlet temperature that takes into account the error term can
be formulated as:
ToP(Comfortable Zone)=ToP-Ge.multidot.(TGT(D)-RMd)/GA (10).
[0166] where ToP is obtained from equation (9), and only equation
(9) is used to calculate the passenger outlet temperature for cabin
temperatures outside the defined comfortable zone.
[0167] However, in another embodiment of the present invention, a
separate error gain can be identified, preferably through empirical
testing, for the passenger's zone that is separate from the error
gain of the driver's zone. Thus, equation (10) becomes
ToP(Gain)=ToP-Ge'(TGT(D)-RMd)/GA (11).
[0168] where Ge' is defined as the passenger's removal gain,
determined preferably through empirical testing.
[0169] The error gains of a preferred embodiment of the present
invention are not constants, although other embodiments of the
present invention can utilize constant error gains. FIG. 5 shows an
example of customized error gain values that address the subjective
nature of rapidly warming or rapidly cooling a vehicle cabin. The
values of FIG. 5 are determined preferably through empirical
testing, and can vary depending on the human factor constraints
and/or the make of the vehicle. From FIG. 5, it is seen that the
gain values vary depending on the estimated room temperature. It is
noted that the present invention is not limited to the values
presented in FIG. 5, since these values can and probably will be
different depending on the results of the empirical testing.
[0170] By using separate variable error gains, transient
temperature performance in a cabin can be controlled so that the
passenger has a sensation of comfort. Thus, the present invention
utilizes a heat flux scheme to deliver heat that is in proportion
to the temperature error.
[0171] Due to the dominance of the driver's zone in the preferred
embodiment of the present invention, there will be situations where
the passenger makes a change to his or her target temperature and
the algorithm does not provide a response that is perceived quickly
enough or perceived to be substantial enough by the passenger. The
present inventor has determined that a preferred embodiment of a
climate control system for an automobile can have the ability to
react aggressively to a change in the target temperature. For
example and not by limitation, if the passenger had previously set
the interior cabin temperature to 75.degree. F. and he or she
changes this setting to be 65.degree. F., it would be desirable for
the climate control system to react in a manner that provides the
sensation to the passenger that the 65.degree. F. temperature has
been attained or quickly will be attained. This could be
accomplished, for example, either by varying the blower speed of
the climate control system or by lowering the outlet temperature on
the passenger's side, or a combination of the two, for a sufficient
period of time to provide the passenger with the sensation that the
control system is quickly and sufficiently reacting to his or her
desires.
[0172] Thus, a preferred embodiment of the present invention
includes a temporary outlet temperature overshoot equation to
provide a stimulus quickly to the passenger that will be
interpreted by the passenger that a change has indeed taken place
in the cabin climate. This is preferably accomplished by an
equation that, when implemented into a control algorithm in a
climate control system, will provide an overshoot or undershoot
outlet temperature that will temporarily increase or decrease the
outlet temperature in comparison to what it would normally be
without this feature. By way of example and not by limitation, this
feature could temporarily position the passenger's mix door to
achieve the appropriate overshoot or undershoot.
[0173] In a preferred embodiment, equations for the temporary
passenger outlet temperature overshoot are best formulated to be
calculated periodically in a timing loop. In a preferred
embodiment, the general overshoot equation for the desired
overreaction margin to the passenger's target temperature change
is:
OverSet=X.multidot.(TGT(P)-FSet),
[0174] where X is a calibration value that sets the strength of the
overshoot, and is determined based on empirical testing directed
towards human factor conditions, and FSet is the time damped value
of the passenger's target temperature, which can be determined from
the equation
FSet=FSet+Y.multidot.(TGT(P)-FSet)
[0175] where Y is a multiplier that is arbitrarily set to allow the
FSet equation to be utilized in an algorithm that obtains the unity
value of FSet in a time period that will preferably maximize the
passenger's comfort, as determined through empirical testing. For
example, if the Y value is 0.1, the FSet equation will reach unity
in approximately 100 loops. The calculated overshoot or undershoot
value is added to the equation for ToP as follows:
ToP'=ToP+OverSet.multidot.[1+K/GA].
[0176] It is noted that the OverSet value can be either positive or
negative, depending on whether an addition or subtraction to ToP is
desired.
[0177] Thus, as the OverSet term is gradually reduced over time,
the ToP' gradually approaches ToP, and eventually, ToP' becomes
equal to ToP, and the overshoot adjustments are effectively no
longer utilized in controlling the climate. By separating the
overadjustment from the basic control equation, the driver's zone
is kept from overreacting to the influence of the overshoot
temperature.
[0178] The possibility exists that in a climate control system
implementing the algorithms described above, the passenger can
reach the limit of the air mix control. For example, if a strong
sun load exists only on the passenger, the full cold air setting
may not be enough to deliver comfort to the passenger, with a low
blower speed that is sufficient for the shaded driver. (It is noted
that in the preferred embodiment, the driver sets the blower speed
for the entire cabin.) Thus, a preferred embodiment of the present
invention includes an algorithm to calculate a minimum airflow that
will satisfy the passenger when the full cold position has been
reached on the passenger side. This algorithm is also applicable to
the full hot condition as well. The following equation for a mass
airflow rate has been developed to compensate for such a
scenario:
GA=K.multidot.(TGT(P)-Ta-q.sub.s(P).multidot.GL/K)/(Capacity
Temperature-TGT(P)) (12)
[0179] where Capacity Temperature, in the preferred embodiment, is
either a temperature about equal to or equal to the constant
cooling device temperature (e.g., in the preferred embodiment, the
constant evaporator temperature of the evaporator of the air
conditioner system) or a temperature about equal to or equal to the
constant heating device air out temperature (e.g., in the preferred
embodiment, the constant heater core air outlet temperature),
depending on whether the air conditioner or heater is operating the
preferred embodiment, these values are predetermined values and not
values obtained by sensors, thus avoiding undesirable blower
fluctuation with air conditioner system cycling and engine coolant
temperature changes.
[0180] Thus, the climate control system of the present invention
can be configured to identify situations where it is necessary to
increase airflow on the passenger side from that set by the driver.
By using equation (12), the minimum airflow value GA can be
calculated. However, it is noted that the present invention
preferably includes an algorithm that limits the airflow calculated
from equation (12) to a value no greater than a predetermined
amount above the driver's zone air flow. By way of example only and
not by limitation, the passenger's airflow can be limited to an
equivalent blower voltage that is no greater than, say 2.0 volts
above the driver's system minimum blower speed in the present air
mode.
[0181] In a preferred embodiment, this minimum blower voltage
applies in parallel with other minimum adjustments. For example,
should the sun load minimum blower speed adjustment exceed the
adjustment determined by equation (12), this adjustment would not
be applied. If equation (12) presented a minimum blower voltage
greater than the sun load adjustment, equation (12) would
effectively set the minimum blower speed.
[0182] In a preferred embodiment of the present invention, the
climate control system utilizes an algorithm or a plurality of
algorithms relating to at least one or more or all of the equations
presented herein. In a preferred embodiment of the present
invention, an algorithm relates to an equation when it utilizes the
equation or a permutation of the equation or a mathematically
equivalent equation or an equation that contains the variables of
the equation as well as additional variables. By way of example, an
algorithm that relies on, for example, equation (6), could utilize
the equation, or could utilize a manipulated equation where, say,
GA is on the left side of the equality and ToD is on the right side
of the equality, etc. Further by way of example, an algorithm that
relies on equation (7) could utilize the equation as seen above, or
an equation with additional terms (by way of example, a term for
internal heat generation by, say, the occupants). Thus, these
equations represent minimums.
[0183] It is noted that in practicing the preferred embodiments of
the present invention, empirical testing is relied on to obtain the
values of various variables (e.g. R). However, it is noted that the
present invention can be practiced by utilizing computational fluid
dynamics based on mathematical models of the interior of a given
cabin and the air flow in the cabin, with or without the use of a
computer, to obtain one or more than one of the variables. Indeed,
any practical method that can be used to obtain satisfactory values
for these variables can be used to practice the present
invention.
[0184] It is again noted that at least some of the above discussed
variables are dependent on the vehicle design, and that these
variables may be different depending on which vehicle in which the
control system is implemented. These variables can be determined
through empirical testing, calibration, or tuning, or through other
types of testing, calibration, or tuning. In a preferred
embodiment, these variables are determined and then treated as
constants, and are not expected to change unless the structure or
components of the automobile are changed.
[0185] It is also noted that the present invention can be used to
automatically determine outlet temperatures and the mass flow rates
by incorporating the present invention into a device, such as by
way of example and not by way of limitation, a computer or a
processor that will determine the outlet temperatures and the mass
flow rates without the need of a human to determine the outlet
temperatures and the mass flow rates. Basically, the present
invention can be practiced with any type of logic circuit or logic
device that can use the present invention to determine outlet
temperatures and mass flow rates.
[0186] The teachings of the present invention can be utilized with
a variety of control systems and controllers as would be apparent
to one of ordinary skill in the art, including the systems taught
in the '990 patent, as would be utilized exactly as taught or
modified by one of ordinary skill in the art to practice the dual
zone climate control system of the present invention, and are
incorporated herein by reference in their entirety. Below is a
discussion of how those teachings could be used to implement the
present invention in a preferred embodiment.
[0187] FIG. 6 shows a flow diagram that illustrates the control
steps for carrying out a control process of the present invention.
The subjective requirements discussed above are contained in
functions that are usually unique for each vehicle. The target
interior temperature and the relationship of air flow and outlet
temperature can be contained in these functions. The air flow that
is desired is initialized at 66 in FIG. 6. An inquiry is made at 68
as to whether the initialization of flow is completed. If it is not
completed, the process will proceed to action block 70, where the
air flow is estimated. If it is completed, the process will proceed
directly to action block 74, where the interior temperature and
ambient temperature values, and the sun load, will be estimated or
measured and, using the estimated/measured values, the desired
target interior temperature(s) as a function of the temperature
setting(s), the ambient temperature, and the sun load, is
calculated at 76. New target values are then computed. The routine
then proceeds to action block 78 where the outlet temperature for
the first and second zone (e.g. driver and passenger zone) is
computed using the heat flux equation, which is stored in a ROM.
This is followed by the execution of the air blending control logic
routine that occurs in, by way of example, a microprocessor, at
block 80.
[0188] A refined air flow estimate GAn is then estimated at 82 to
determine the new air flow. This air flow estimate is based on such
factors as, by way of example and not by way of limitation, human
factor constraints and air restriction effects. The airflow
refinement may include blower speed minimum considerations related
to sun load and other subjective considerations including
constraining the blower speed to the outlet temperature. Further,
the air blending action may create differences in the airflow that
can be accounted for in the logic. An adjusted air flow then is
computed at 84, based on the refined airflow estimate GAn. An
inquiry then is made at 86 to determine whether the difference
between the new air flow and the old air flow is less than a limit
that is predetermined by calibration. If it is not less than that
limit, the routine then will be repeated as the function flow
returns to action block 74. The routine will repeat itself until
the difference between the old air flow and the new air flow is
less than a certain limit. At that time, the logic will then
calculate an air distribution logic and a blower speed logic, as
shown at blocks 88 and 90, respectively.
[0189] The routine of FIG. 7 can be used to control the climate in
the situation described above where an occupant of, say, the second
zone, for example, a passenger (or, in other embodiments, an
occupant of the first zone) reaches the limit of the air mix
control. (e.g. a strong sun load exists only on the passenger and
the full cold air setting is not enough to deliver comfort to the
passenger.) At block 92, the heater and/or evaporator capacity
temperature is measured or estimated. At action block 94, the
interior temperature value(s), ambient temperature value, and the
sun load will be estimated or measured and, using that estimated
interior temperature value(s), the desired target outlet
temperature(s) as a function of the temperature setting(s), the
ambient temperature, and the sun load, is calculated at 98.
[0190] At block 100, the target outlet temperature(s) is determined
based on either the capacity temperature or the subjective
temperature. The subjective temperature is derived from the
statistical understanding of customer requirements. In the case
where the system temperature limits (capacity) are exceeded by the
customer requirements, the heater or evaporator temperatures are
applied in place of the subjective requirements. For example, if
the subjective outlet temperature requirement was 70.degree. F. but
the heater is only 65.degree. F., the 65.degree. F. would be used
in the calculation. The "passboost" logic (see block 106) is a
provision to aid in ensuring that a minimum blower speed is
provided to a given zone dependent on the capacity temperature
limits of the evaporator and the heater. Using the target outlet
temperature determined at block 100 in combination with equation
12, the mass airflow rate GA requirement is determined at block
102. It is noted that the actions of blocks 98 and 100 can be
accomplished both through the use of equations to calculate or
iterate a value of the target interior temperature and/or the
outlet temperature, a look up table, alone or in combination with
fuzzy logic, can be used to obtain these values. If the embodiment
of the present invention includes an algorithm that limits the
airflow to a value no greater than a predetermined amount above the
first zone (e.g. driver zone) air flow, an airflow limit adjustment
is made at block 104. Further, this section can also provide values
when the division at block 102 is indeterminate. At 106, a
passboost logic routine is executed to ensure that a minimum blower
speed is provided to a given zone dependent on the capacity
temperature limits of the evaporator and the heater identified
above. If the logic routine does not identify a minimum blower
speed, room temperature error correction logic will be utilized at
block 108 to adjust the outlet temperature and blower speed to
increase or decrease the room temperature to the target temperature
quickly. The routine will then proceed to block 110 where the air
blend logic will be calculated, followed by the calculation of the
air distribution logic at block 112 and the calculation of the
blower speed logic at block 114. In the event that a minimum blower
speed is needed at 106, control blocks 108, 110 and 112 will be
bypassed and the routine will proceed directly to control block 107
where the special airflow minimum limit will be set. After this,
the logic will then calculate the blower speed logic at 114. It is
further noted that the routine of FIG. 7 can allow for an
additional specification of air flow and outlet temperature. After
interior temperature is estimated, the routine will proceed to
compute the desired interior temperature by taking into account
ambient air temperature, temperature setting, and the sun load. The
computation of the desired steady state outlet temperature can then
be computed, after which the routine can proceed to compute
interior temperature error gain for air flow. An interior
temperature error gain for outlet temperatures can then be
calculated, which can be used to calculate the current desired
outlet temperature.
[0191] It is noted that the present invention can be practiced with
a variety of air conditioning systems and system components, such
as that taught in U.S. Pat. No. 6,272,873.
[0192] Given the disclosure of the present invention, one versed in
the art would appreciate that there may be other embodiments and
modifications within the scope and spirit of the present invention.
Accordingly, all modifications attainable by one versed in the art
from the present disclosure within the scope and spirit of the
present invention are to be included as further embodiments of the
present invention. The scope of the present invention accordingly
is to be defined as set forth in the appended claims.
* * * * *