EUROPEAN COMMISSION
ENTERPRISE AND INDUSTRY DIRECTORATE-GENERAL
Industrial Innovation and Mobility Industries
Automotive industry
Brussels, 13/09/2012
ENTR.F1/KS
WLTP-DTP: various open items to be decided for final GTR draft
EU positions
1.
Definition of test mass and payload factor
1.1.
Certification test
The EU suggests testing a vehicle representative for a certification family at a
test mass high (TMH) and, only if required by the vehicle manufacturer, test
mass low (TML). In such case, two sets of road load factors should be
obtained for the vehicle weight equalling TMH and TML and the respective
road load factor sets should be used for the two tests.
TMH = MEV + 100 kg + MAO + PLF x RPLTMH
TML = MEV + 100 kg + PLF x RPLTML
Here:
- MEV is the mass of the empty vehicle without any options
- 100 kg should represent the weight of the driver including some basic
luggage
- MAO is be the total mass of all options offered by the vehicle manufacturer
for the given vehicle
- PLF should be the payload factor (0 < LF < 1). PLF should correspond to
the average load of a vehicle determined by traffic statistics and may be
different for M and N category vehicles. The current proposal of the EU
(based on preliminary traffic data) would be a PLFM = 0,15 and LFN = 0,35.
These values may however be revised upon statistical evidence
- RPLTMH/TML should be the remaining maximum payload for the vehicle, if
equipped with all options (TMH) or no option (TML), with respect to the
maximum allowable vehicle weight
According to the worst case principle, criteria pollutant emissions of all
vehicles of the certification family should be determined for a test mass
equalling TMH and the respective road load factors.
Commission européenne, B-1049 Bruxelles / Europese Commissie, B-1049 Brussel - Belgium. Telephone: (32-2) 299 11 11.
Office: BREY 10/027. Telephone: direct line (32-2) 2958557. Fax: (32-2) 2969637.
E-mail: nikolaus.steininger@ec.europa.eu
If the representative vehicle has not been tested at TML, CO2 emissions/fuel
consumption emissions of all vehicles of the certification family should be
determined for a test mass equalling TMH and the respective road load
factors.
If the representative vehicle has been tested at TML and TMH, for
determining the CO2 emissions/fuel consumption of a given vehicle within a
certification family the CO2 emissions/fuel consumption measured for TMH
and TML should be interpolated linearly and the emission/fuel consumption
values should be read off for the actual test mass TM of the vehicle:
TM = MEV + 100 kg + MO + PLF x RPLTM,
where MO is the mass of the options installed in the given vehicle.
1.2.
Labelling
For European labelling purposes it may be considered to extrapolate the CO2
emission/fuel consumption vs. test mass curve in order to obtain values for a
wider range of payloads that could be communicated to the user as a range.
However, the technical validity of such extrapolation would have to be further
investigated for European certification purposes (outside the WLTP process).
2.
Temperature lab-set point
For European certification purposes the EU intends to introduce a correction factor
that should describe the increase of CO2 emissions at average European ambient
temperatures (around 10° C) with respect to the WLTP test temperature. Most likely
this correction will be obtained by interpolating CO2 emission results from the
WLTP at low temperature test (- 7° C) or by performing additional CO2 emissions
measurements at the average European ambient temperature on a larger vehicle
group comprising several certification families and combining the results with the
specific WLTP CO2 emissions for individual certification vehicle families.
Obviously the result for the correction factor will improve if the upper interpolation
point will be closer to the average European ambient temperature. Therefore the EU
strongly suggests a set point for the WLTP test temperature of 22° C. It should be
noted that this temperature is way above the average ambient temperatures in Japan
and the US and probably not higher than the average Indian ambient temperature.
3.
Fan speed
The EU supports the following Dutch proposal "WLTP-DTP-LabProcICE-138”,
which was slightly amended and agreed by LabProcICE:
"A current of air of variable speed shall be blown over the vehicle. The set point of
the linear velocity of the air at the blower outlet shall be equal to the corresponding
roller speed above roller speeds of 5 km/h. The deviation of the linear velocity of the
air at the blower outlet shall remain within ± 5 km/h or ± 10 % of the corresponding
roller speed, whichever is greater."
4.
Tyre choice and conditioning
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The EU supports to use a tyre with the worst energy efficiency class (A to G) as
defined in Annex I of Directive (EC) 1222/2009, out of the set of tyres, with which
the vehicle is equipped by the vehicle manufacturer. If in the set of tyres, with
which the vehicle is equipped by the vehicle manufacturer, several tyres have got
the same worst efficiency class (e.g. F), out of this sub-set a tyre with the lowest
tyre class (e.g. C1, not C2) has to be chosen for the WLTP.
For the tyre conditioning the EU supports in general the Dutch proposal "WLTPDTP-LabProcICE-139 - tyre condition proposal _ NL".
5.
Number of bags
The EU supports the use 4 bags (1 bag per cycle part) for the measurement gaseous
and 1 filter for PM emissions.
Justification: for consumer information and possibly more specific regulation
gaseous emissions (in particular CO2 and NOx) should be identified and recorded
for all 4 test phases (L, M, H, Ex-H/L) separately. However, for PM emission this
principle would lead to a significant loss of accuracy due to the small PM quantities
collected, therefore just 1 filter should be taken for the entire test.
6.
Road load determination methods
Currently three alternative measurement methods are envisaged to be included in
the WLTP-GTR for the determination of the vehicle road load:
– Coast down
– Use of torque meters for measuring the torque applied to the vehicle wheels
– Wind tunnel measurements
Road load parameters have a strong influence on the CO2 emissions measured on
the test cycle. It is therefore important that they are determined in a realistic and
well-defined manner. In particular it has to be ensured that ambiguities of the
procedure cannot be used to pick "optimal" road load parameters for individual
vehicles. As a consequence the equivalence of the 3 methods has to be
demonstrated, if they are to be included as alternatives in the WLTP-GTR. Basically
two ways forward could be envisaged:
(1)
Demonstrate with existing data or a test program the equivalence of the 3
methods. If such programme is to be launched the first WLTP-GTR draft
could contain the 3 methods "in brackets", i.e. make them subject to the
outcome of the test programme. The test programme would then only have
to be finalised in the second half of 2013 before the formal adoption of the
WLTP-GTR in WP.29.
(2)
The coast down road load determination is defined as the reference method.
A vehicle manufacturer could use one of the other methods for a given
certification family if he demonstrates the equivalence of this method to the
coast down. This could be done e.g. by performing back-to-back tests on a
larger vehicle group comprising several certification families. Of course
criteria for determining these larger vehicles groups would have to be
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defined in the WLTP-GTR, but there would be no immediate need for a test
program.
In addition it is foreseen to determine the road load by the use of fixed values from a
table. The EU proposes that the default factors should represent worst case to
prevent an incentive to use it instead of road load determination measurement
methods.
WLTP-DHC: Japanese proposal of 4th September 2012 for WLTC, EU positions
For vehicles with a maximum speed < 120 km/h and a power/mass ratio > [34 kW/t] the
Japanese proposal could be accepted provided Japan delivers a more detailed valid
technical justification taking into account the shift of the lower power/mass ratio
boundary due to considering the actual test mass high (TMH) of the vehicle instead of its
curb mass.
For vehicles with a maximum speed > 120 and < 135 km/h and a power/mass ratio > [34
kW/t] the EU considers the application of an extra high speed cycle part for its own
certification as essential. Whether this will be the Ex-H2 or Ex-H3 part will still have to
be decided, most likely not at WLTP but at EU certification level. Japan is requested to
provide more detailed valid technical justification for its proposal. Depending on the
analysis of this justification the EU could possibly accept the application of the Ex-H2,
Ex-H3 or L (as suggested by Japan) part as a regional option. It should also be noted that
European vehicle manufacturers may still raise some objections due to concerns about
distortions of the Japanese vehicle market. The final decision on the Ex-H2 vs. Ex-H3
part to be applied for these vehicles also depends on the provisions still to be defined for
vehicles that cannot follow parts of the driving curve (e.g. driving at full throttle).
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