WLTP-05-05e

8/11/2019 WLTP-05-05e

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WLTP Phase 1B

Main Open Issues Road and Dyno Load

Presentation at WLTP IG Meeting Geneva 8.1.2014

Open Issues Road and Dyno Load- K. Kolesa

Working paper No. WLTP-05-05

8/11/2019 WLTP-05-05e


2 Titel oder Name, Abteilung, Datum

Open Issues Phase 1B for WLTP Road and Dyno Load

4 3.2. wind tunnel criteriageneral review required

close link to #18 YES

4 4.1. wind conditions general review for on board anemometry

validation

measurements

required

NO

4 4.3. coast down procedure

review of definitions and selection of

speed range, speed points, reference

speeds for RLD and dyno load setting

to be discussed,

then modify if

necessary

NO

4 4.3.2.

on board anemometry based

coast down method e.g.

4.3.2.6.1.

review of the method (comments IR 85 -

87, 92)to be developed NO

4 4.4. torque meter methodgeneral review of torque meter method

(comment IR 95, IR 132)

to be reviewed,

then modify if

necessary

NO

4.4.2.2. torque meter method ascending ? or descending ? to be decided NO

4 4.5.5. road load curve correct ionuse always three coefficients, formulae to

be developed (comments IR 101 - 103)

to be reviewed,

then modify if

necessary

NO

4 5.2. default road load parameter

Industry objects to current parameters.

Based of future data the parameters can

be reviewed and adapted

(LabProcICEdoc 269)

to be reviewed,

then modify if

necessary

NO

4 6. wind tunnel method for RLD method to be developed to be developed YES

4 7.3.4.alternative warm up

proceduredefinition of family or procedure to be developed NO

4 8.2.3.2.chassis dyno load setting

with torque meter method

review and/or development of a method

with 3 coefficients,

10 N criteria to be checked/applied

transfer of road to dyno load - clarification

needed

to be reviewed,

then modify if

necessary

NO

4,

App.

1

2.3.

The simulated road load

calculation for each reference

speed v_j

postpone to phase-1b

to be reviewed,

then modify if

necessary

NO


YES

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3

On-Board Anemometry for RLDWLTP Annex 4 § 4.1.1.1.2

► Road load determination of vehicles on road has to consider actual windinfluence by measuring ambient wind speeds . For low wind speeds a stationary

anemometry is sufficient. Measuring under higher wind speed conditions is only

allowed using onboard wind speed measurement.

► This anemometry method is of regional importance using test tracks with a

more open structure and higher wind speed conditions. Therefore this methodwas introduced in WLTP.

► The maximum permissible wind speed conditions were discussed at length in

Phase 1A and it was concluded to perform further investigations in accuracy of

correction functions to obtain a robust and equivalent anemometry method.

► Contact persons. A. Rijnders (NL) and C. Hosier (OICA)

Initial proposal is expected in meeting # 8, final decision in meeting #8


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4

Windtunnel Criteria

WLTP Annex 4 § 3.2

► Background: The combined approach is based on measurement data

for the vehicle with lowest and highest cycle energy demand. The

vehicles between these extremes can be measured or calculated with

data of mass, tire rolling resistance and aerodynamic resistance of

available options.

► Aerodynamic data of available options can be measured on road with ahigh uncertainty or better in a wind tunnel. Therefore basic criteria for

windtunnel characteristics were introduced in WLTP.

► Discussions with CP revealed need for a further review of these criteria

as some windtunnel actually cannot fulfill the requirements. Especially

the requirement for moving ground belt and the air pressure coefficient

have to be discussed with CP’s.

► Contact Person: BMW

Initial proposal expected at WLTP meeting #8, decision in meeting #12

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5

Windtunnel / Chassis dyno as alternative RLD method

WLTP Annex 4 § 6

► Current WLTP provides 4 methods for road load determination:

1. Coast down method2. Torquemeter method

3. Use of windtunnel/Chassis Dyno

4. Calculation of road load based on vehicle parameters

► Method (3) was reserved in gtr, but not developed yet.

► Measurement principle: Driving resistance of vehicles on road is caused by aerodynamic

drags and resistance of tires and mechanical/electrical drags. Vehicle aerodynamic

resistance is measured in wind tunnel with specified characteristics, rolling resistance is

determined at chassis dynamometer equipment. The discrete evaluated forces can be

superposed to obtain the driving resistance.

► Accuracy is expected to be far better than on road measurements due to lack of

influencing ambient factors, like wind, road, temperatures.► Critical is the definition of windtunnel and chassis dyno equipment. The equivalency to the

method 1 has to be shown by validation testing. Calibration for measurement equipment

is to be defined.

► Contact Person is BMW, initial proposal is expected in WLTP meeting #6, decision in

meeting #12


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6

Torque meter method as alternative RLD methodWLTP Annex 4 § 4.4

► Current WLTP provides 4 methods for road load determination:

1. Coast down method

2. Torquemeter method

3. Use of windtunnel/Chassis Dyno

4. Calculation of road load based on vehicle parameters

► Method (2) was introduced as an alternative method to coasting down a vehicle

► Measurement principle: Driving resistance of vehicles on road is caused by

aerodynamic drags and resistance of tires and mechanical/electrical drags. Vehicleaerodynamic resistance is measured at constant speed points and the energy demand

for superseding the driving resistance is determined by special torquemeters between

driving axle and tire.

► Advantage is measurement of driving resistance under positive torque. Parasitic drags

(e.g. electric braking or regeneration) during deceleration phase of vehicle can be

avoided.

► Critical is the validation of equivalency to coast down method. Validation testing

required. Calibration of measurement equipment is to be validated.

► Contact person are TNO and C. Hosier (OICA) , initial proposal is expected in WLTP

meeting #9, decision in meeting #9.

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Alternative Warming Up Procedure on Dyno

WLTP Annex 4 § 7.3.4

► Background: Road Load of vehicle has to be simulated on chassis dynoto obtain similar conditions as in real life. For comparison of dyno load

with road load the vehicle has to be in comparable temperature

conditions

► Current WLTP provides a prescription for warming up the vehicle

preceding dyno load determination

► For alternative warming up procedures the equivalency criteria and the

applicable family definition have to be reviewed.

► Contact Person: Yamaguchi, Japan

Initial Proposal expected at WLTP meeting #6, final decision in

meeting#7


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8

Calculation of default road load based on vehicle parameters

WLTP Annex 4, § 5

►

As an alternative for determining road load with the coast down ortorque meter method , a calculation method for default road load

parameters may be used.

► Situation: Industry objects to current defined parameters. Based on

future data the parameters can be reviewed and adapted

► Contact Person: A. Rijnders (NL)

Initial proposal expected in WLTP meeting #8, final decision in meeting

#9


WLTP-05-05e

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