1

WLTP-DHC-05-05

WLTC* Construction

Proposed by JapanGRPE/WLTP-IG/ DHC subgroup

14 October 2010

*) WLTC : Worldwide harmonized Light-duty driving Test Cycle

2

WLTP-DHC-05-05

Contents

1. Cycle Construction

2. Cold/Hot Start Weighting

3. Gear Shift Points

Table of Contents

3

WLTP-DHC-05-051. Cycle Construction

1. Cycle Construction

1.1. Current Test Cycle in EU, US and Japan

1.2. Requirement on Test Cycle

1.3. Proposed Cycle Construction

1.4. Justifications

4

WLTP-DHC-05-051.1. Current Cycle Construction

NANA

Cold start and

Hot startJAPAN

NANA

Cold start

EU

Hot startHot startHot startCold start Hot

US

AC testAggressive modeMotorwayUrban / Rural

10 m

in.s

oak

According to WLTP-DHC-05-04, Urban/Rural/Motorway phase will be converted to Low/Middle/High phase respectively.

(independent test with preconditioning)

5

WLTP-DHC-05-05

FlexibilityUnique test procedure

HEVRegeneration systemEV range

Unique VehicleCity commuterLow power vehicle

1.2. Requirement on Test Cycle

RepresentativenessDriving characteristicCold start (e.g. 6 or 12 hours soak)Hot start

intermediate soak (e.g. 10 min. soak) warm up (e.g. 15 min. drive @ 60kph)

PerformanceEmissionFuel consumption/GHG

Target Area

Test effectivenessEquipment restriction

Chassis dynamometerBag analysis durationMinimum sample volume

Test flexibilityHuman respect

6

WLTP-DHC-05-05

Low phase Middle phase High phase

1.3. Proposed Cycle Construction

Cold start

Hot start

Low phase Middle phase

TL TM

TL + TM = equal to or less than 1372 sec.

( )( ) ( ) ( )

( )( ) ( ) ( )∑∑∑

∑

∑∑∑∑

×+×+×

×=

×+×+×

×=

iiHiH

iiMiM

iiLiL

iiMiM

M

iiHiH

iiMiM

iiLiL

iiLiL

L

TwTwTw

Tww

TwTwTw

Tww

,,,,,,

,,

,,,,,,

,,

TL : TM = ML WW :

TH= equal to or less than 765 sec.

can be skipped if same condition as cold start phase High phase test can be conducted

after middle phase or independently

7

WLTP-DHC-05-051.4. Justifications

RepresentativenessDriving characteristicCold startHot startintermediate soak (e.g. 10 min. soak)

warm up (e.g. 15 min. drive @ 60kph)

PerformanceEmissionFuel consumption/GHG

FlexibilityUnique test procedure

HEVRegeneration systemEV range

Unique VehicleCity commuterLow power vehicle

Test effectivenessEquipment restriction

Chassis dynamometerBag analysis durationMinimum sample volume

Test flexibilityHuman respect

Low phase should be first

No WF in each phase is best solution.Each phase duration should be based on the traffic volume ratio.

Current longest cycle duration is first step.Independent high phase test is inevitable.

Either condition is acceptable by adjusting the Cold/Hot weighting factor. The “warm up”condition is more effective for testing flexibility.

8

WLTP-DHC-05-052. Cold/Hot Start Weighting

2. Cold/Hot Start Weighting

2.1. How to obtain real-world emissions ?

2.2. Average Emission per Trip

2.3. Cold Start Trip Ratio

2.4. Calculation of Cold Weighting Factor

2.5. Summary

2.6. Required Data

9

WLTP-DHC-05-052.1. How to obtain real-world emissions ?

Emission that should be evaluated

Average emission per trip＝

◆Requirements

Average emission per trip

Emission during cold start trip

Emission during hot start trip

Emission under cold condition

Emission under hot condition

◆Detail of average emission per vehicle trip

Emission under hot condition

10

WLTP-DHC-05-052.2. Average Emission per Trip and Cold Weighting Factor

Total Emission Etotal (g/km) formula is as following.

Cold start emission

under cold condition

Cold start emission under hot condition

0 km Dcycle Dtrip

Cold start trip

×Rcold + ×(1 - Rcold) Hot start emission

0 km Dtrip

Hot start trip

EC(g/km)

EH(g/km)

EH(g/km)

ECT(g/km)

(*) ECT = (EC * Dcycle + EH * (Dtrip – Dcycle))/ Dtrip

Etotal = ECT * Rcold + EHT * (1 – Rcold)

= (Dcycle*Rcold/Dtrip) * EC + (1-Dcycle* Rcold/Dtrip) * EH

= WFC * EC + (1 - WFC) * EH

WFC = Dcycle * Rcold / Dtrip

WFc: Cold start weightingRcold: Cold start trip ratioDtrip: Average one trip distance (km)Dcycle: Cycle distance (km)ECT: Cold start trip emission (g/km)EHT: Hot start trip emission (g/km)EC: Cold start emission (g/km)EH: Hot start emission (g/km)

EHT(g/km)

=

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WLTP-DHC-05-052.3. Cold Start Trip Ratio

Ambient temp.

Freq

uenc

y

Soak time

◆Frequency of soak time

◆Cold start factor

Coo

lant

tem

p. d

rop

ratio

Coo

lant

tem

p.

Soak timei

Cold start trip ratio Rcold :

[ ]∑ ⋅= )i(F)i(FR coldsoakcold

Where,

Rcold: Cold start trip ratio (= Average cold start emission increment ratio)

Fsoak: Frequency of soak time

Fcold: Cold start factor (Coolant temp. drop ratio )

Generate the cold start trip ratio by multiplying the soak time distribution and the coolant temperature drop ratio as the emission increase ratio

Fsoak(i)

Fcold(i)

12

WLTP-DHC-05-052.4.1. Calculation Sample

Low/Mid. Hot

Cold Start Trip

★Low/Mid. cold + Low/Mid hot + High hot

High Hot

MCT

ECT

(DT * WLM – DC,LM) * EH,LM

WHWLMWF

EH,LM EH,HEC,LM

Emission(g/km)

Dtrip * WLM – DC,LM

Dtrip * WH

Dtrip * WLM

DC,LM

DC,LM * EC,LM (Dtrip * WH) * EH,H

Mass (g)

Dtrip

Distance (km)

ECT = MC,T / Dtrip

= (DC,LM * EC,LM + (Dtrip * WLM – DC,LM) * EH,LM + (Dtrip * WH) * EH,H) / Dtrip

◆Emission during cold start trip ECT (g/km)

Low/Mid. Cold

13

WLTP-DHC-05-052.4.2 Calculation Sample

EHT = WLM * EH,LM + WH * EH,H

◆Emission during hot start trip EHT (g/km)

Etotal = ECT * Rcold + EHT * (1 – Rcold)

= (DC,LM * Rcold / Dtrip) * EC,L + (WLM – DC,LM * Rcold / Dtrip) * EH,L + WH * EH,H

= WFLM,C * EC,L + WFLM,H * EH,L + WFH,H * EH,H

◆Total emission Etotal (g/km)

WFLM,C = DC,LM * Rcold / Dtrip

WFLM,H = WLM – DC,LM * Rcold / Dtrip

WFH,H = WH

◆Cold/Hot weighting factor

★Low cold + Low hot + Middle hot + High hot (conti.)

Low/Mid. Hot

EH,LM (g/km)

High Hot

EH,H (g/km)

Dtrip * WHDtrip * WLM

14

WLTP-DHC-05-052.5. Summary

◆Required information/dataInvestigate the following two items based on actual vehicle usage

Distribution of soak timeDriving distance per trip

Investigate the following based on engine bench testCoolant temperature drop ratio

Other factorsTest cycle distanceThe ratio of traffic volume in each phase (L/M/H)

In Japan, these figures are obtained based on survey and traffic senses.

◆Calculation processCalculate cold start trip ratio

Generate the cold start ratio by multiplying the soak timedistribution and the coolant temperature drop ratio

Calculate cold start WFGenerate the cold start WF based on average one trip distancecold start trip ratio and test cycle distance

15

WLTP-DHC-05-052.6. Required Data -1

◆Distribution of soak time

Light duty commercial vehiclePassenger Car

100.0

4.0

3.0

5.0

18.0

6.0

3.0

2.0

3.0

5.0

10.0

12.0

7.0

11.0

10.0

(%)

100.0Total

4.048.0 -

3.024.0 -48.0

5.012.0 – 24.0

18.09.0 – 12.0

6.06.0 – 9.0

3.05.0 – 6.0

2.04.0 – 5.0

3.03.0 – 4.0

5.02.0 – 3.0

10.01.0 – 2.0

12.00.75 – 1.0

7.00.5– 0.75

11.00.25 – 0.5

10.00 – 0.25

(%)(hour)

FrequencySoak time

0 2 4 6 8 10 12 14 16 18 20

0 – 0.25

0.25 – 0.5

0.5– 0.75

0.75 – 1.0

1.0 – 2.0

2.0 – 3.0

3.0 – 4.0

4.0 – 5.0

5.0 – 6.0

6.0 – 9.0

9.0 – 12.0

12.0 – 24.0

24.0 -48.0

48.0 -

Soa

k tim

e (h

r)

Frequency (%)

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WLTP-DHC-05-052.6. Required Data -2

◆Cold start factor

01100

(℃)

Coolant temp.

20

20

20

20

20

20

20

22

25

29

36

40

47

73

(℃)

Coolant temp.

Cold start factor

Cold start factor

1.048.0 -

1.024.0 -48.0

1.012.0 – 24.0

1.09.0 – 12.0

1.06.0 – 9.0

1.05.0 – 6.0

1.04.0 – 5.0

0.983.0 – 4.0

0.952.0 – 3.0

0.901.0 – 2.0

0.820.75 – 1.0

0.780.5– 0.75

0.700.25 – 0.5

0.410 – 0.25

(-)(-)(hour)

Light duty commercial vehiclePassenger car

Soak time

0

20

40

60

80

100

120

0 2 4 6 8 10 12

Time (hr)C

oola

nt te

mp.

(℃)

17

WLTP-DHC-05-053. Gear Shift Points

3. Gear Shift Points3.1. Analysis Method3.2. How to define the gear position ?3.3. Definition of Shift Change3.4. Factor Analysis / Frequency Distribution3.5. Regression Analysis3.6. Analysis Sample (JC08)

18

WLTP-DHC-05-053.1. Analysis Method

1 1 1 1 1 1

22 2 2 2 2 2 2

3 3 3 33 3

33

4 4 4 4 4

5 5 5

C C

CC

C

C0

20

40

60

80

0 100 200 300 400 500 600 700

Speed (km/h)

Time (s)

In-use data collection

Factor analysisFrequency distribution

Regression AnalysisDevelop Shift point equation

Validation

G(x)=a*V+b*A+・・・・

0%

5%

10%

15%

0 10 20 30 40

2nd：F

requency

Speed (km /h)

Developed gear shift points based on in-use survey to represent the real driving behavior.

ex. 2nd Gear Analysis

19

WLTP-DHC-05-053.2. How to define the gear position ?

In case of manual gear shift, the formula for calculating vehicle speed would be the following if the clutch was engaged.

Consequently, gear position can be defined by calculating gear ratio during driving

ft iiNer2V

⋅⋅π

=

where,

V: Vehicle speed (km/h)

Ne: Engine speed (1/min)

r: radius of tire

it: Gear ratio

if: final reduction ratio

20

WLTP-DHC-05-053.3. Definition of Shift Change

Shift up_1: Clutch release point for up-shiftingShift up_2: Clutch engage point after putting in higher gearShift down_1: Clutch release point for down-shifting or neutral

01020304050607080

Veh

icle

spe

ed (k

m/h

)

Vehicle speed Shift up 1_Clutch offShift up 2_Clutch on Shift down 1_Clutch off

0

1000

2000

3000

4000

Eng

ine

spee

d (1

/min

)

Engine speed Shift up 1_Clutch offShift up 2_Clutch on Shift down 1_Clutch off

0

1

2

3

4

5

6

0 10 20 30 40 50 60 70 80 90Time (s)

Gea

r pos

ition

(-)

Gear position Shift up 1_Clutch offShift up 2_Clutch on Shift down 1_Clutch off

21

WLTP-DHC-05-053.4. Factor Analysis / Frequency Distribution

Calculate the vehicle speed in each gear position (both up-shift and down-shift), then generate various frequency distribution by each vehicle category and analyze the factors that effect shift operation.

Vehicle speed frequency distribution（0 ≤ V ≤ 100 km/h，1km/h step）Vehicle acceleration frequency distribution （-10 ≤ a ≤ 10 km/h/s, 1km/h/s step）Engine speed frequency distribution（600 ≤ r ≤ 6000 rpm, 100rpm step）Standardized engine speed frequency distribution （0 ≤ r ≤ 100 %, 10 % step）

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WLTP-DHC-05-053.5.1. Regression Analysis

Develop the shift point equation by Stepwise selection method

No. of gear

Refer slide 3.5.2Drive train coefficient (DTC)

Wn = Curb weight / GVW

1: Petrol, 2: Diesel, 3: LPG,,,

1: M1, 2: N1, 3: N2,,,

Remark

Normalized vehicle weight

Torque to mass ratio (Nm/t)

Power to mass ratio (kW/t)

Maximum torque (Nm)

Maximum power (kW)

Displacement (cc)

Gross vehicle weight (kg)

Maximum pay load (kg)

Curb weight (kg)

Fuel type

Vehicle category

Acceleration (km/h/s)

Normalized engine speed (%)

Engine speed (1/min)

Vehicle speed (km/h)

Gear position

Explanatory variableDependent variable

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WLTP-DHC-05-053.5.2. Drive Train Coefficient （DTC）

DTC : Drive Train Coefficient

Power Train

Drive Train

Engine Transmission

Differential Gear

Tire

imif

r

2πr / (im * if) ： running distance per engine speed (m)

r ： tire radius (m)im ： gear ratioif ： final reduction gear ratio V ： vehicle speed （km/h）Ne ： engine speed （rpm）

601000

NeV

ifimr2

×=×π 0

0.2

0.4

0.6

0.8

0 1 2 3 4 5

Run

ning

dis

tanc

e

a

n en

gine

revl

utio

n (m

)

Gear Position

Vechile A

Vehicle B

Vehicle C

y = DTC * G(x)

G(x)

Final reduction gear

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WLTP-DHC-05-053.6.1. Analysis Sample (JC08) - shift up speed

0%

5%

10%

15%

20%

0 10 20 30

1st：Frequency

Speed (km /h)

Vehicle A

Vehicle B

Vehicle C

Vehicle D

Vehicle E

Vehicle F

Vehicle G

Vehicle H

Vehicle I

Vehicle J

Vehicle K

0%

5%

10%

15%

0 10 20 30 40

2nd：Frequency

Speed (km /h)

0%

2%

4%

6%

8%

10%

0 20 40 60

3rd：Frequency

Speed (km /h)

0%

2%

4%

6%

8%

10 30 50 70 90 110

5th：Frequency

Speed (km /h)

0%

1%

2%

3%

4%

5%

40 60 80 100 120

6th：F

requency

Speed (km /h)

0%

2%

4%

6%

8%

10 30 50 70 90

4th：F

requency

Speed (km /h)

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WLTP-DHC-05-053.6.2. Analysis Sample (JC08) - downshift speed

0%

20%

40%

60%

0 10 20 30

1st：Frequency

Speed (km /h)

Vehicle A

Vehicle B

Vehicle C

Vehicle D

Vehicle E

Vehicle F

Vehicle G

Vehicle H

Vehicle I

Vehicle J

Vehicle K

0%

10%

20%

30%

0 10 20 30 40

2nd：Frequency

Speed (km /h)

0%

5%

10%

15%

20%

0 20 40 60

3rd：Frequency

Speed (km /h)

0%

1%

2%

3%

4%

5%

6%

0

20

40

60

80

100

120

5th：Frequency

Speed (km /h)

0%

1%

2%

3%

0

20

40

60

80

100

120

6th：Frequency

Speed (km /h)

0%

2%

4%

6%

8%

0 20 40 60 80

4th：Frequency

Speed (km /h)

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WLTP-DHC-05-053.6.3. Analysis Sample (JC08) - Explanatory variable of shift up

1 2 3 4 5 6 7

0.752 Speed

0.815 Speed Acceleration

0.844 Speed Acceleration Normalizedvehicle weight

0.847 Speed Acceleration Normalizedvehicle weight DTC

0.851 Speed Acceleration Normalizedvehicle weight DTC

Normalizedvehicle weight

@ running order

0.851 Speed Acceleration Normalizedvehicle weight DTC

Normalizedvehicle weight

@ running order

Engine Speed @Max. torque

0.852 Speed Acceleration Normalizedvehicle weight DTC

Normalizedvehicle weight

@ running order

Engine Speed @Max. torque

Engine speed @Max. power

R2Explanatory variable

⇒After completion of all data acquisition, the explanatory variable will be determined based on stepwise selection method.

27

WLTP-DHC-05-053.6.4. Analysis Sample (JC08) - Explanatory variable of downshift

1 2 3 4 5 6 7

0.552 Speed

0.629 Speed Engine speed

0.834 Speed Engine speed DTC

0.841 Speed Engine speed DTC Acceleration

0.845 Speed Engine speed DTC Acceleration Maximumtorque

0.846 Speed Engine speed DTC Acceleration Maximumtorque

Normalizedvehicle weight

0.848 Speed Engine speed DTC Acceleration Maximumtorque

Normalizedvehicle weight

Enginecapacity

R2Explanatory variable

⇒After completion of all data acquisition, the explanatory variable will be determined based on stepwise selection method.

28

WLTP-DHC-05-053.6.5. Analysis Sample (JC08) - Gearshift equation

Shift up

Shift down

G(x) :Gearshift equationV :Speed in km/hA :Acceleration in km/h/sWn :Normalized vehicle weight (Curb weight / GVW)E :Engine speed in rpmDTC :Drive train coefficient

DTCWAVxG nup ⋅−⋅−⋅−⋅+= 36.381.1139.00576.096.2)(

DTCEAVxG down ⋅−⋅−⋅−⋅+= 9.2500129.0043.00924.012.5)(

⇒After completion of all data acquisition, the gearshift equation for WLTC will be developed.

29

WLTP-DHC-05-053.6.6. Analysis Sample (JC08) – Final Shift Points

Vehicle CategorizationPassenger CarLight Duty Commercial Vehicle

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.4 0.5 0.6 0.7 0.8 0.9 1.0Nomalized vehicle weight Wn

Driv

e tra

in c

oeffi

cien

t

① ① ① ① ① ① ① ① ① ① ①

②

②

②

②②

②②

② ② ② ②②

③ ③ ③③

③ ③③

③

③③③

④ ④④

④

④

④ ④

⑤ ⑤⑤

⑥

C

C

C C C

C

C CC

C C

0

10

20

30

40

50

60

70

80

90

100

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300Time (s)

Spee

d (k

m/h

)

① ① ① ① ① ① ① ① ① ① ①

②②

②

②

②

② ②

② ② ②② ②

③③

③③

③③

③③ ③

③ ③③

④ ④ ④④

④ ④

⑤⑤

⑤ ⑤

⑥

C C

CC C

C

C C

C

C C

0

10

20

30

40

50

60

70

80

90

100

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300Time (s)

Spe

ed (k

m/h

)

◆for Passenger cars ◆for Light duty commercial vehicles

Average of PCWn=0.80, DTC=0.11

Average of LDCVWn=0.58, DTC=0.09