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Presentation Outline
Impact of A/C on Fuel Consumption
Approaches to A/C Power Saving- A/C Cycle & System Efficiency Improvement- A/C Control Efficiency Improvement- Coordination With Powertrain
- Vehicle Thermal Management Improvement
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Influence of A/C on Fuel Consumption
A/C OffA/C Off A/C on(yearly)A/C on(yearly)
F u e
l C o n s u m p
t i o n
( k m
/ L )
F u e
l C o n s u m p
t i o n
( k m
/ L )
55
1010
1515 Actual Running Mode:
Compact Car LA4: Stop Ratio 17% 9 %
Electric load is alsoa major item.Electric load is alsoa major item.
Idle up (11)Idle up (11)Blower (38)Blower (38)Cooling Fan (9)Cooling Fan (9)
Clutch (3)Clutch (3)
Fuel Consumption Increase Ratio (%)Fuel Consumption Increase Ratio (%)
Yearly
(9%)
Yearly
(9%)
Compressor (39)Compressor (39)
ComponentsCompressor, Condenser, etc
Influence of VehicleThermal ManagementRunning Condition
Constant Speed,Acceleration/Deceleration
Idling,
ComponentsCompressor, Condenser, etc
Influence of VehicleThermal ManagementRunning Condition
Constant Speed,Acceleration/Deceleration
Idling,
Impact onFuel Consumption
Impact onFuel Consumption
10Evaporator Outlet Air Temperature ( oC)
LowBlower Speed
FreshFresh / Recirculated Air
0Sun Load (W/m 2)
50Humidity (%)
25Temperature (oC)
Yearly
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Impact on Fuel Consumption
119 38 3
Compressor (39)Compressor (39)
Fuel Consumption Increase Ratio (%)
Yearly(9%)
Yearly(9%)
Re-Entry of Heated Air (10-15 o C) (4) Re-Entry of Heated Air (10-15 o C) (4)
Increase Evaporator Inlet Air Temperature (5-10 o C) (4) Increase Evaporator Inlet Air Temperature (5-10 o C) (4)
Thermal Management Improvement:Evaporator Air Inlet Temperature Reduction Preventing Hot Air RecirculationThermal Management Improvement:Evaporator Air Inlet Temperature Reduction Preventing Hot Air Recirculation
Assumption by Thermal Data at Idling and 40 km/h Running Assumption by Thermal Data at Idling and 40 km/h Running
Large Effect When Idling and Decelerating (Accelerating In Summer)Large Effect When Idling and Decelerating (Accelerating In Summer)
Coordination Control with PowertrainCoordination Control with Powertrain
A/C Control Considering Running ConditionA/C Control Considering Running Condition
Fuel Consumption Increase Ratio (%)Fuel Consumption Increase Ratio (%)
Constant SpeedConstant Speed Accelerating Accelerating DeceleratingDecelerating IdlingIdling
Yearly(9%)
Yearly(9%)
LA4LA4
00 2525 5050 100100
2222 2222 3838 1818
7575
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Approach to A/C Power Saving
A/C Cycle &System Efficiency
Improvement(including
components)A/C ControlEfficiency
Improvement
Coordinationwith Powertrain
ThermalManagementImprovement
Impact on A/C Fuel Consumption
A/C Cycle , System & Components
Personal Preference
Vehicle HeatRunning Condition
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A/C Cycle System Efficiency Improvement Subcool Cycle & Improvement of Subcool condenser
Improvement of Compressors Efficiency & Variable
Displacement Compressor System
A/C Control improvement
Coordination with Powertrain
Vehicle Thermal Management Improvement
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1980 1985 1990 1995 2000 2005 201040
60
80
100
120
140
160
180Q/F = Performance/(core width x core height)
Serpentine
Multi-Flow
Condenser Efficiency Improvement
Q / F
Subcool type
High-performance Subcool
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SubcoolReciever
Condenser
CompressorEvaporator
Exp.Valve
Enthalpy
P r e s s u r eSubcooling
Increase InEffective Refrigerant
ImprovedCooling Performance
GAS
Liquid
Operating Principle of Subcool Cycle
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Condenser Performance Improvement
2. Increased Core Effective Area2. Increased Core Effective AreaNewestNewest
16 mm16 mm
1.7 mm1.7 mm
7.8 mm7.8 mm
16 mm16 mm
1.0 mm1.0 mm5.4 mm5.4 mm
ConventionalConventional
(approximate dimensions)(approximate dimensions)
(Improved Tube & Fin Efficiency)(Improved Tube & Fin Efficiency)1. Enhance Heat Transfer 1. Enhance Heat Transfer
SubcoolSubcool
QQQ + QQ + Q
Q Q
Subcool Effect Gives Q Extra CoolingSubcool Effect Gives Q Extra Cooling
Mollier Diagram Subcool EffectMollier Diagram Subcool Effect
Tank HeightTank Height Side Plate HeightSide Plate Height
Effect100
90
80
Old Current
11% Down
C o m p r e s s o r
L o a
d R a t
i oConventionalConventional
NewestNewest
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Compressor Efficiency Improvement
19801980 19851985 19901990 19951995 20002000
YearYear
0.70.7
C o m p r e s s o r
E f f i c i e n c y
( % )
C o m p r e s s o r
E f f i c i e n c y
( % )
20052005
HFC134a
Latest Compressor Exceeds
70%.
Latest Compressor Exceeds
70%.
0.60.6
0.50.5
0.40.4
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Continuously Variable Displacement CompressorMax Displacement
Ps
Pc
Pd
Partial DisplacementPd
Pc
Ps
Pc = Ps
Pc Ps
Piston
Shaft ControlValve
Swash-Plate
Piston Stroke Max
Piston Stroke Max~Min
Piston Stroke
Control Valve
Control Valve
Piston Stroke
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Divide into Compressor Efficiencyand Cycle Performance
theory
practice theory
practice
Comp.efficiency
ad
Cycle
practice
practice
Ps
Ts
IsentropicProcess
Pd Td
theory
enthalpy
P r e s s u r e
practice
System
Analysis Method
Variable Displacement Comp System is improved.
Characteristics of Variable Displacement Compressor
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0 100%/ON-OFF
T o r q u e
Variable DisplacementComp.
T o r q u e
Better
In the performancecontrolled region, thevariable displacementcompressor systemshows a better
performance than thefixed compressor system
Effect of Variable Displacement Compressor System
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A/C Cycle System efficiency improvementA/C Control improvement
Power saving control
Humidity control
Coordination with Powertrain
Vehicle Thermal Management Improvement
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0 10 Ambient Temperature TAM ( oC)
5 15 20 25 30 350
5
10
15
TEO (o
C)
T a r g e
t o
f A i r T e m p .
a f t e r
E v a p o r a
t o r
Power SavingDemist
Economy Control Logic
Current:Internal
Variable
ComfortHumidity
Conventional Control (Internal Variable Compressor)
Tin20deg.
3deg.
15deg.Te
Tout
T e m p
.
Tin
Evap.
Te
H/CTout
Tin20deg.
12deg.15deg.Te
Tout
T e m p .
Tin
Evap.
Te
H/CTout
Power saving Control (External Variable Compressor) Effect
1
P o w e r
C o n s u m p
t i o n r a
t i o
0
-30%
Economy Conventional
ExternalVariable
Power saving Control using external variable compressor
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Humidity Control (1)
Evaporator Evaporator Heater Heater corecoreBlower Blower
CowlCowl
Condenser Condenser Compressor Compressor
00551010
151520202525
00 55 1010 1515 2020 2525 3030 A b s o
l u t e H u m
i d i t y ( g
/ k g
A b s o
l u t e H u m
i d i t y ( g
/ k g
) )
Temp.Temp.
100%100%
80%80%
60%60%
40%40%
20%20%DehumidifyDehumidify
--Control the outlet air temp. & humidityControl the outlet air temp. & humidityby changing the evaporator temperature (TEO)by changing the evaporator temperature (TEO)
adopted by PRIUSadopted by PRIUSRelative Humidity
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High pressure Ph
Evap outAir temp Te
Thermistor
Condenser
Evaporator
Comp.
ControlValve
High-sidePressure
sensor
A/C Switch
Configuration
Ambient temp Ta
Exp.
Ambient sensor
A/C ECUCalculate:Duty ratio
Comp power
Ambient temperature ( ) E v a p o u
t a i r
t e m p .
( ) Demist
HumidityComfort Zone
Windshield humidity
target: 90%
Cabin humidityTarget: 60%
NoReheat
0 5 15 25 35
12
0
M i n i m u
m
d e h u
m i d i f
i c a t i o n
w/oHumiditycontrol
Effect
WithHumiditycontrol
Demist Line
Cabintemperature
and Humidity
Humidity Control (2)
Power Consumption Ratio
-20%
Conditions: 25 C-50% Blower: M1
With Humidity Control
w/o Humidity Control
0 1
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A/C Cycle System efficiency improvement
A/C Control improvement
Coordination with Powertrain
Vehicle Thermal Management Improvement
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Cooperativecontrol E/G-A/C withexternal compressor
Displacement Controldue to Cooling performance
Displacement controldue to Compressor power
Engine(Driving)
Comp.
DrivingconditionDriversrequest
Output
Air-condition
Comp.Power
Compressor management
Coordination with Powertrain Approach
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Deceleration Control
Time
V e
h i c l e
s p e e
d
A c c e l
e r a t i o
n D e c e l e r a t i o n
Cruising
Stop(Idle)
Time
Store cold airDischarge
the cold air
Improve fuelconsumptionFuel cut
C o o
l i n g
P e r
f o r m a n c e
Time
Much Power
saving withminimumperformance
reduction
Current(Ps control)
New control
Reduce comp displacementduring Acceleration
C o m p p o w e r
c o n s u m p
t i o n
A / C f u e l
c o n s u m p
t i o n
Compressor is run for requiredcooldown performance with
minimum power consumption.
Idle speed is suitably controlledbased on compressor power
consumption.
C o m p p o w e r
c o n s u m p
t i o n
Store the cool air duringDeceleration(Displacement: Maximum)
Control Pattern for Compressor Power ControlAcceleration Control
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A/C Cycle System efficiency improvement
A/C Control improvement
Coordination with Powertrain
Vehicle Thermal Management Improvement Reduction of Vehicle Heat Prevention of Heated Air Re-entry into Condenser
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Heat Insulation (Roof)
Heat Insulation (Pillar) Solar Radiation Absorption Glass (Rear)
Solar radiation Absorption Glass (Side)
Effect
- 3%Solar Radiation Absorption Glass (Rear, Side)
- 6%Heat Insulation (Roof, Pillar)
Effect of Heat load reductionItem
1. Reduction of Vehicle Heat Load
Vehicle Thermal Management Improvement
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Shutter Stops Heated Air Re-Entry
Lower Cover Lower Cover
Shutter
Heated Air
Engine
EffectCondenser Inlet Air Temperature Reduced by 6 oC
2. Prevention of Heated Air Re-entry into Condenser
Shutter
Vehicle Thermal Management Improvement
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Example of Application to VehicleToyota COROLLA
P o w e r C
o n s u m p t i o n
R a
t i o
1
0.9
0.8
0.7
0.6
0.5
1993Model
2001
Nearly 20%
Power Consumption of Compressor After 30minutes at Idling
Subcool SystemSerpentine Condenser
Subcool Condenser
Compressor Improvementad 0.62
ad 0.68
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Many A/C Power Saving Technologies Have Been Developed; A/C Cycle & System Efficiency Improvement A/C Control Efficiency Improvement Coordination With Powertrain Vehicle Thermal Management Improvement
Some Already Adopted in Mass-production VehiclesTechnologies Will Be Further Expanded in the Future.
Summary