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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