U.S. patent application number 11/464216 was filed with the patent office on 2008-02-14 for methods of optimizing vehicular air conditioning control systems.
This patent application is currently assigned to GM GLOBAL TECHNOLOGY OPERATIONS, INC.. Invention is credited to Peter A. Donis, Gregory A. Major, Mark D. Nemesh, Lawrence P. Ziehr.
Application Number | 20080034767 11/464216 |
Document ID | / |
Family ID | 39049196 |
Filed Date | 2008-02-14 |
United States Patent
Application |
20080034767 |
Kind Code |
A1 |
Ziehr; Lawrence P. ; et
al. |
February 14, 2008 |
Methods of Optimizing Vehicular Air Conditioning Control
Systems
Abstract
Air conditioning system controls are optimized for an air
conditioning system having a compressor in IC engine vehicles and
in hybrid or fuel cell vehicles having electric drive motors by
first determining the operating temperature of at least one of the
following vehicle components: engine coolant and transmission oil
for all types of vehicles, and for hybrid or fuel cell vehicles
also determining the operating temperature of inverter coolant and
the electric drive motors. At least one operating temperature is
then compared to lower and upper temperature limits. If the
operating temperature is outside of the temperature limits air
conditioner heat load is reduced by at least one of the following
steps: increasing cabin air recirculation, reducing cabin blower
speed and reducing air conditioner compressor capacity. Subsequent
to reducing air conditioner heat load, selected operating
temperature or temperatures are monitored to determine if the
operating temperature exceeds the upper temperature limit or
limits. If the operating temperature or temperatures exceed the
upper limit or limits the compressor is shut off.
Inventors: |
Ziehr; Lawrence P.;
(Clarkston, MI) ; Donis; Peter A.; (Oak Hill,
VA) ; Major; Gregory A.; (Farmington Hills, MI)
; Nemesh; Mark D.; (Troy, MI) |
Correspondence
Address: |
GENERAL MOTORS CORPORATION;LEGAL STAFF
MAIL CODE 482-C23-B21, P O BOX 300
DETROIT
MI
48265-3000
US
|
Assignee: |
GM GLOBAL TECHNOLOGY OPERATIONS,
INC.
Detroit
MI
|
Family ID: |
39049196 |
Appl. No.: |
11/464216 |
Filed: |
August 14, 2006 |
Current U.S.
Class: |
62/180 ;
62/228.4 |
Current CPC
Class: |
B60H 1/00878 20130101;
B60H 2001/3282 20130101; B60H 1/00849 20130101; B60H 1/3208
20130101; B60H 2001/327 20130101; B60H 1/00828 20130101; B60H
2001/3266 20130101; B60H 1/00385 20130101; B60H 1/00735 20130101;
B60H 1/00764 20130101 |
Class at
Publication: |
62/180 ;
62/228.4 |
International
Class: |
F25D 17/00 20060101
F25D017/00; F25B 49/00 20060101 F25B049/00 |
Claims
1) A method of optimizing an air conditioning system control in a
vehicle comprising momentarily reducing air conditioner condenser
heat load via electric compressor speed control, forced cabin
recirculation, and/or reduced cabin blower speed during transient,
high ambient and high propulsion system load events.
2) A method according to claim 1, wherein all three of electric
compressor speed control, forced cabin recirculation, and reduced
cabin blower speed are performed.
3) A method of optimizing an air conditioning system control in an
air conditioning system for a vehicle, comprising the steps of: I)
checking: 1) whether the temperature of the engine coolant is
higher than a first engine coolant temperature limit and lower than
a second engine coolant temperature limit, 2) whether the
temperature of the transmission oil is higher than a first
transmission oil temperature limit and lower than a second
transmission oil temperature limit, Ia) if the answer to 1 or 2 is
yes, then repeating I), Ib) if the answer to 1 or 2 is no, then
proceeding to step II), II) reducing air conditioner heat load by:
1) increasing cabin recirculation of air 2) reducing cabin blower
speed 3) reducing air conditioner compression III) after step II),
checking 1) whether the engine coolant temperature is higher than
the second engine coolant temperature limit; and 2) whether the
transmission oil temperature of the transmission oil is higher than
the second temperature limit; IIIa) if the answer to 1 or 2 is yes,
then shutting off the A/C compressor, setting a flag and then
repeating step III), IIIb) if the answer is no, then checking for
the presence of the flag, IIIbi) if the flag is present, performing
cabin recirculation, limiting cabin blower speed and reducing
compressor capacity followed by repeating step I), IIIbii) if no
flag is present, repeating step I).
4) The method according to claim 3, wherein the temperature limits
are predetermined values.
5) The method according to claim 3, wherein in step II) cabin
recirculation of air is increased by X %, cabin blower speed is
increased by Y %, and compressor capacity is reduced by Z %.
6) The method according to claim 3, wherein X, Y and Z are
predetermined values.
7) The method according to claim 3, wherein X, Y and Z are
calculated values.
8) A method of designing vehicles comprising determining propulsion
cooling system size which achieves predetermined performance while
performing the method according to claim 3.
9) The method according to claim 8, wherein the cooling system size
is reduced from a size the cooling system would have been without
the vehicles performing a method according to claim 3 while having
the same predetermined performance, comprising: reducing radiator
cooling size by core thickness reduction, fin density reduction, or
core face area reduction; and reducing fan motor power.
10) A method of optimizing an air conditioning system control in an
air conditioning system for a hybrid or fuel cell vehicle,
comprising the steps of: I) checking: 1) whether the temperature of
the engine coolant is higher than a first engine coolant
temperature limit and lower than a second engine coolant
temperature limit, 2) whether the temperature of the transmission
oil is higher than a first transmission oil temperature limit and
lower than a second transmission oil temperature limit, 3) whether
the temperature of the inverter coolant is higher than a first
inverter coolant temperature limit and lower than a second electric
motor temperature limit, and 4) whether the temperature of the
electric motor is higher than a first electric motor temperature
limit and lower than a second electric motor temperature limit, Ia)
if the answer to all of 1), 2) 3) and 4) checked is yes, then
repeating I), Ib) if the answer to any of 1), 2) 3) or 4) is no,
then proceeding to step II), II) reducing air conditioner heat load
by: 1) increasing cabin recirculation of air, or 2) reducing cabin
blower speed, or 3) reducing air conditioner compressor capacity,
III) after step II), checking 1) whether the engine coolant
temperature is higher than the second engine coolant temperature
limit; 2) whether the transmission oil temperature of the
transmission oil is higher than the second temperature limit; 3)
whether the inverter coolant temperature of the inverter coolant is
higher than the second inverter coolant temperature limit; 4)
whether the electric motor temperature of the electric motor is
higher than the second electric motor temperature limit; IIIa) if
the answer to any of 1), 2) 3) or 4) is yes, then shutting off the
A/C compressor, setting a flag and then repeating step II), IIIb)
if the answer to all of the parameters that have been checked is
no, then checking for the presence of the flag, IIIbi) if the flag
is present, performing cabin recirculation, limiting cabin blower
speed and reducing compressor capacity followed by repeating step
I), IIIbii) if no flag is present, repeating step I).
11) The method according to claim 3, wherein the temperature limits
are predetermined values.
12) The method according to claim 3, wherein the temperature limits
are calculated values.
13) A method of designing vehicles comprising determining
propulsion cooling system size which achieves predetermined
performance while performing the method according to claim 10.
14) The method according to claim 13, wherein the cooling system
size is reduced from a size having the same predetermined
performance, comprising: reducing radiator cooling size by core
thickness reduction, fin density reduction, or core face area
reduction; and reducing fan motor power.
15) The method of claim 14 wherein the vehicle is a hybrid or fuel
cell vehicle and the method further comprises: reducing power
electronics radiator size by core thickness reduction, fin density
reduction, and core face area reduction, and reducing electric
motor cooler size by reduced core thickness, fin density reduction,
and core face area reduction.
16) A method of optimizing an air conditioning system control for
an air conditioning system having a compressor in hybrid or fuel
cell having an electric drive motor, the method comprising:
determining the operating temperature of at least one of the
following vehicle components: engine coolant, transmission oil,
inverter coolant and the electric drive motor; comparing the at
least one operating temperature to lower and upper temperature
limits; if the operating temperature is outside of the temperature
limits reducing air conditioner heat load by at least one fo the
following steps: increasing cabin air recirculation, reducing cabin
blower speed and reducing air conditioner compressor capacity;
subsequent to reducing air conditioner heat load, monitoring the
operating temperature to determine if the operating temperature
exceeds the upper temperature limit, shutting off the compressor if
the operating temperature exceeds the upper limit; repeating the
step of determining the operating temperature, and restarting the
compressor once the operating temperature is below the upper
temperature limit to recirculate conditioned air a limited blower
speed on reduced compressor capacity.
17) The method of claim 16 wherein the operating temperatures of at
least two of the vehicular components are determined.
18) The method of claim 16 wherein the operating temperatures of
three of the vehicular, components are determined.
19) The method of claim 16 wherein the operating temperatures of
four of the vehicular components are determined.
Description
FIELD OF THE INVENTION
[0001] The present invention is directed to methods of optimizing
vehicular air conditioning control systems. More particularly, the
present invention is directed to such methods which result in
reduced propulsion cooling system size in non-hybrid vehicles and
lower operating temperature for coolant loops in hybrid and fuel
cell vehicles.
BACKGROUND OF THE INVENTION
[0002] Conventional vehicle propulsion cooling systems include heat
exchangers and fans, the size of which is based on propulsion
system losses. Losses are absorbed by engine coolant, engine oil
and transmission oil. Those losses typically are momentarily
exacerbated when the vehicle operates on a steep gradient and/or is
towing a trailer, especially when the ambient air temperature is
high. With respect to hybrid and fuel cell vehicles, propulsion
cooling loops require lower operating temperatures than
conventional power train vehicles.
[0003] Air conditioning condensers are typically the first heat
exchangers in the CRFM (Condenser Radiator Fan Module) air stream.
Propulsion cooling system heat exchangers typically include engine
radiators and transmission oil coolers. Hybrid and fuel cell
vehicles also include inverter radiators and electric motor
radiators. These heat exchangers are typically disposed downstream
of the A/C (Air Conditioning) condenser, and are therefore affected
by A/C condenser heat load.
[0004] In current production vehicles having power train controls,
when propulsion cooling systems approach maximum temperature
limits, A/C system control is typically limited to A/C compressor
interrupt. A/C compressor interrupt results in a complete loss of
cabin cooling because the A/C system simply shuts off when
propulsion system thermal limits are reached.
SUMMARY OF THE INVENTION
[0005] In view of the aforementioned considerations, the present
invention optimizes air conditioning systems for vehicles by
momentarily reducing A/C condenser heat load during transient, high
ambient temperature/high propulsion system load events, thereby
allowing an overall reduction in propulsion cooling system
size.
[0006] Reducing the required propulsion cooling system size
includes at least one of the following possibilities:
[0007] 1) reducing radiator cooling size, e.g., by core thickness
reduction, fin density reduction, and/or core face area
reduction;
[0008] 2) reducing electric cooling fan size, e.g., by reduced fan
motor power;
[0009] 3) for hybrid and fuel cell vehicles the possibilities also
include: [0010] 3a) reducing power electronics radiator size, e.g.,
by core thickness reduction, fin density reduction, and/or by
reducing core face area reduction, and/or [0011] 3b) reducing
electric motor cooler size, e.g., by reduced core thickness, fin
density reduction, and/or core face area reduction.
[0012] In another aspect, there is a reduction of mass and cost of
propulsion cooling systems for the following vehicles: hybrid
vehicles that have either an electric A/C compressor or an external
capacity control A/C compressor; fuel cell vehicles that have
either an electric A/C compressor or an external capacity control
A/C compressor; and conventional power train vehicles that have an
external capacity control A/C compressor; as well as conventional
power train vehicles that have a fixed displacement A/C
compressor.
[0013] In a further aspect, the realization of cabin air
conditioning is maintained during propulsion system thermal
excursions and improved fuel economy is realized due to, for
example, reduced CRFM (Condenser Radiator Fan Module) electric fan
power and CRFM mass.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Various other features and attendant advantages of the
present invention will be more fully appreciated as the same
becomes better understood when considered in conjunction with the
accompanying drawings, in which like reference characters designate
the same or similar parts throughout the several views, and
wherein:
[0015] FIG. 1 is a perspective view of a controller according to
the invention in combination with an automotive vehicle, wherein in
the illustrated example the vehicle is a hybrid vehicle;
[0016] FIG. 2 is a flow chart outlining operation of the controller
of FIG. 1;
[0017] FIG. 3 is a diagrammatical illustration of the controller
used with a strong-hybrid arrangement;
[0018] FIG. 4 is a diagram illustrating results for a specific
simulation in a hybrid or non-hybrid vehicle;
[0019] FIG. 5 is a graph of theoretical eThermal simulation results
for an A/C system optimization of a propulsion cooling system of
reduced size in a non-hybrid vehicle;
[0020] FIG. 6 is a graph of eThermal simulation results for a model
of an A/C system optimization in a propulsion cooling system of
reduced size used in a non-hybrid vehicle;
[0021] FIG. 7 is a tabulation of results for examples of amounts of
condenser heat load reduction showing positive impacts to the
vehicles, and
[0022] FIG. 8 is a graph of eThermal simulation results for an A/C
system optimization of reduced propulsion cooling system size in a
non-hybrid example.
DETAILED DESCRIPTION
[0023] Referring now to FIG. 1, a controller 10 in a hybrid vehicle
11 selectively connects an IC engine 13 or an electric traction
motor 14 to the drive wheels 15 of the hybrid vehicle. The
controller 10 is mounted at any convenient location in the vehicle
11, but typically is mounted in an engine compartment 16.
Controllers such as cabin temperature controllers and controllers
for HVAC systems including a compressor 17 and a condenser 18 are
preferably installed in the cabin, for example, within the
instrument panel, or under the seats, or maybe installed in the
trunk.
[0024] FIG. 2 is a flow chart outlining the step-by-step operation
of a controller 10 according to the invention. In the "initial
step," the controller 10 checks a first truth table 21 to determine
if any of the following conditions are true: [0025] 1) whether the
operating temperature of the engine coolant is higher than a
temperature limit T1A and lower than a temperature limit T2A, or
[0026] 2) whether the operating temperature of the transmission oil
is higher than a temperature limit T1B and lower than a temperature
limit T2B, or [0027] 3) whether the operating temperature of the
inverter coolant is higher than a temperature limit T1C and lower
than a temperature limit T2C, or [0028] 4) whether the operating
temperature of the electric motor is higher than a temperature
limit T1D and lower than a temperature limit T2D.
[0029] Information on various other parameters applicable to a
given system may also be checked by the controller in its decision
making process. The temperature limits T1A, T2A, T1B, T2B, T1C,
T2C, T1D and T2D, are predetermined based on design choices for a
given vehicle 12. Temperature limits T1C, T2C, T1D and T2D apply
only to hybrid and fuel cell vehicles.
[0030] If the answer to all of the parameters checked in the
initial step by the truth table 21 is "YES," then the A/C system
operation is within normal ranges and the controller 10
periodically repeats the same initial step of checking the
parameters.
[0031] If the answer to any of the parameters in the initial step
21 is "NO," then the controller 10 responds in step 22 by:
[0032] 1) increasing cabin recirculation of air by X %,
[0033] 2) reducing cabin blower speed by Y %, and/or
[0034] 3) reducing compressor capacity by Z %.
These adjustments achieve a reduction of A/C condenser heat load.
Preferably, all three, i.e., increasing cabin recirculation of air
by X %, reducing cabin blower speed Y %, and reducing compressor
capacity Z % are performed to achieve optimization according to the
invention. Alternatively, any one or more, or preferably two of the
three procedures in step 22 are performed. The percent values for
X, Y, Z are predetermined based on design choices for a given
vehicle 12. Alternatively, the X, Y, Z values are based on a
calculation in the controller 10 based on various data, such as
vehicle operating parameters/conditions.
[0035] Following the above steps 21 and 22 which achieve a
reduction of A/C condenser heat load, the controller 10 checks a
second truth table 23 to determine whether any of the following
conditions are true:
1) the operating temperature of the engine coolant is higher than
the high temperature limit T2A, or 2) the operating temperature of
the transmission oil is higher than the high temperature limit T2B,
or 3) the operating temperature of the inverter coolant is higher
than the high temperature limit T2C, or 4) the operating
temperature of the electric motor is higher than the high
temperature limit T2D. The controller 10 may also check information
on various other parameters not in the illustrated truth table 23
applicable to a given system. The values the high temperature
limits T2A-T2D can be the same as the temperature limits in
pre-corresponding order listed in the initial step 21 of the
controller 10, or alternatively the values can be different. For
example, the temperature values of the first predetermined values
T2A-T2D, other than the values in the first step 21, can be a
function of the temperature values of the first step.
[0036] If the answer to any of the parameters is "YES in the second
truth table 23, the A/C compressor is shut off and a Flag AA is set
in step 24. Then the controller 10 repeats checking the parameters
discussed above. If the answer to all of the parameters that have
been checked is "NO," then the controller 10 checks as to whether
Flag AA in an A/C restart mode.
[0037] If the Flag AA is present, the A/C system is restarted by
the A/C restart step 24 to perform cabin recirculation at limited
cabin blower speed and reduced compressor capacity. Preferably, all
three, i.e., cabin recirculation plus limited cabin blower speed
and reduced compressor capacity are performed to achieve
optimization according to the invention. Alternatively, any one or
more preferably two of the three may be performed. The cabin
recirculation, limited cabin blower speed and reduced compressor
capacity is limited and/or reduced by predetermined amounts, or
alternatively are a function of full capacity values, e.g., a
percentage of the same or are based on various changing vehicle
performance parameters/conditions, for example, a calculation based
on data provided to the controller 10. Following the check of the
Flag AA 25, the controller 10 rechecks the truth table 21.
[0038] FIG. 3 depicts a hybrid air conditioning system, in which an
air stream 30 enters the system from the front end of the vehicle
12 and passes through an A/C condenser 31. Downstream of the A/C
condenser 31, the air stream 30 passes through a transmission oil
cooler 32 and a power electronics heat exchanger 33. Transmission
oil 35 circulates between the transmission oil cooler 32 and
transmission 36. Fluid 39 circulates from the power electronics
heat exchanger 33 to a power train power electronics and/or
electric traction motor 40 followed by vehicle power electronics
41. Further downstream, the air stream 30 passes through an engine
radiator 43 positioned in front of an electric fan package 44,
which engine radiator cools coolant fluid from the IC engine 13 of
FIG. 1.
[0039] FIG. 4 illustrates a hybrid simulation in which the air
conditioning load is decreased according to the previously
discussed arrangement illustrated in FIG. 2. In FIG. 4, there is
heat rejection in front of the engine radiator 43 due to the
conditioned air 30 passing through both the auxiliary transmission
oil cooler 32 and the AC condenser 31. When the load on the AC
condenser 31 is reduced using the method of FIG. 2, there is a
reduction of less than 10% in the air available to cool coolant in
the engine radiator 43 due to heat rejection by both the AC
condenser 31 and the auxiliary transmission oil cooler 32. This
results in approximately 10% reduction in the temperature of the
coolant from the internal combustion engine 13 (FIG. 1) to the
engine radiator 43, which reduces power train cooling content,
i.e., the mass, dimensions and thus cost of the heat exchanger (the
engine radiator 43) and the cooling fan package 44 (FIG. 2). This
feature is available for both hybrid and non-hybrid vehicles as
well as fuel cell vehicles in which the internal combustion engine
13 is replaced by a fuel cell.
[0040] FIG. 5 is a graph of results using data for an A/C system
optimization for a propulsion cooling system of reduced size in a
non-hybrid vehicle. Conditioned air results in KW and Temperature T
(C) are graphed as a function of time and include condenser outside
air (OSA) 51 introduced into the cabin; condenser recirculated air
52; condenser air out temperature 53; conditioner recirculated air
out temperature 54 and engine rpm/100 55. As is seen in FIG. 5, by
using the method of FIG. 2, there is an approximately 50% reduction
in conditioner heat load 51 from heat load of the cabin OSA 51
compared with the heat load of cabin recirculation air 52. There is
also about a 10% reduction in conditioner air out temperature 54
when using the method of FIG. 2.
[0041] FIG. 6 is a graph similar to FIG. 5, but also plotting the
temperature 57 of coolant into the engine radiator 43 during
cooling of outside air, as well as the temperature 59 of coolant
into the engine radiator 43 during cooling of recirculating air
from the cabin of the vehicle. It is seen from FIG. 6 that by
employing the method of FIG. 2, wherein cabin recirculation air is
increased, while cabin blower speed and compressor capacity are
reduced during recirculation, the temperature 59 of coolant into
the engine radiator 43 is substantially lower than the temperature
57 of coolant into the engine radiator when outside air is being
cooled. This difference allows for a smaller radiator size, as well
as fan package size in non-hybrid vehicles. In hybrid or fuel cell
powered vehicles, condensers run by electric motors consume less
power by increasing cabin recirculation while reducing cabin blower
speed and compressor capacity.
[0042] FIG. 7 is a chart tabulating examples of condenser heat load
reduction resulting improvements to the vehicle efficiency. The
chart shows that for hybrid/fuel cell vehicles with electric A/C
compressor, the average A/C condenser heat load reduction by
forcing cabin recirculation and having reduced compressor capacity
is about 11%, which impacts the vehicle by a reduction in
transmission sump temperature and a reduction in engine radiator
inlet coolant temperature.
[0043] For non-hybrid vehicles with a belt driven compressor, where
cycling is fixed if using a displacement compressor, displacement
can be reduced if using a variable capacity compressor. There are
also improvements in efficiency. As is set forth in the chart of
FIG. 7, the average A/C condenser heat load reduction by forcing
cabin recirculation and having reduced compressor capacity is about
50%. This results in a reduction in engine radiator inlet coolant
temperature or a reduction in Engine Radiator Core Thickness. This
provides a potential production cost option in designing and/or
manufacturing an automotive vehicle.
[0044] FIG. 8 illustrates results in a graph for an A/C system
optimization for reduced propulsion cooling system size in a
non-hybrid example. Condenser heat load 81 in watts (w) and engine
rpm 82, as well as vehicle speed 83 in kph and condenser air out
temperature 84 in .degree. C. are plotted as a function of time
with cabin HVAC in a recirculation mode 92 versus an outside air
(OSA) mode 94 with the vehicle on 0% grade. The data shows that
when the system is in a cabin recirculation mode, the condenser
load 92 is lower than when the system is in cabin in OSA mode 94.
The method of FIG. 8 is carried out by a controller operated in
accordance with the method of FIG. 2. While the data plotted is for
a non-hybrid vehicle, the same principles apply for hybrid and fuel
cell vehicles.
[0045] From the foregoing description, one skilled in the art can
easily ascertain the essential characteristics of this invention,
and without departing form the spirit and scope thereof, can make
various changes and modifications of the invention to adapt it to
various usages and conditions.
* * * * *