WLTP-10-17-rev1e BMW, 10.04.2015 Christoph Lueginger WLTP Road Load Family Proposal on a family definition for road load determination

The road load influences WLTP Road Load Family The road load influences influences on road load assessed by mass combined approach rolling resistance aerodynamics drivetrain type (2WD/4WD) defined in road load family drivetrain losses Annex 4 gearbox type electric machine uses interpolation family definition, if not decoupled not relevant for road load The engine has no influence on the road load values (f0,f1,f2), as it is decoupled, apart from: weight, aerodynamic (and indirectly rolling resistance) influences.  But they are covered by the calculation of the individual road load coefficients! As the test vehicle selection is based on a worst case approach (already defined in Annex 4), drivetrain losses are considered properly anyway. WLTP Road Load Family, BMW, 10.04.2015

WLTP Road load family Introduction Road load testing for each interpolation family causes a lot of effort, although differences between interpolation families could be calculated easily, as long as they are related to road load (i.e. RR, mass, aerodynamics). Introducing a road load family can be done quite easily, as it uses available definitions. The only new part, which needs a definition, is the allowed interpolation range. It has to be slightly bigger than the allowed range for the interpolation family to include for mass and aerodynamic differences of different engines. Conforming that interpolation range and the concept itself, it was agreed to perform validation tests. See minutes of Geneva-meeting 06/2014: WLTP Road Load Family, BMW, 10.04.2015

performed measurements WLTP road load Family Validation Program, introduction Four vehicles have been selected (from what was available!) and some road load parameters have been adjusted in order to cover the needed range as good as possible and within the constraints of the road load family criteria (e.g. n/v was 11%, same drivetrain: RWD, AT). performed measurements selection coast down 1-2 tests, average taken, 11/2014 and 03/2015 weight adjusted within vehicle limits, to get an equal distribution aerodynamic drag as it is rolling resistance (according to GTR) wheels selected within optional equipment vehicle 318dA weight  aero RR vehicle 320dA weight  aero  RR vehicle 328iA weight  aero  RR  vehicle 435iA weight  aero  RR  WLTP Road Load Family, BMW, 10.04.2015

Validation Program, validated range WLTP road load Family Validation Program, validated range Proposed maximum range of 35% was validated as far as it was possible with the available vehicles. WLTP Road Load Family, BMW, 10.04.2015

Validation Program, road load comparison WLTP road load Family Validation Program, road load comparison Not only the values, but also the shape matches very well between coast down and calculated result. Please notice, that here only F1F1F2 is shown, mass influence has to be considered on top. WLTP Road Load Family, BMW, 10.04.2015

Validation Program, result and conclusion WLTP road load Family Validation Program, result and conclusion  Calculation of road load is at least as accurate as coast down testing, and very close to its result (0% and 0.5% cycle energy). Difference can be a result of coast down variance as well.  This maximum error of 0.08 MJ corresponds to approx. 0.5 g/km CO2 within WLTP.  Road load family is validated! WLTP Road Load Family, BMW, 10.04.2015

from WLTP-DTP-LabProcICE-172 - Comparison RLD flatbelt_VW.pdf WLTP Road Load Family definition proposal Starting from the interpolation family and dropping the engine related issues (decoupled parts). Input of Japan can be included in the definition, if not already covered by other parts of the GTR. Fine-tuning can be still done. from WLTP-DTP-LabProcICE-172 - Comparison RLD flatbelt_VW.pdf WLTP Road Load Family, BMW, 10.04.2015

from WLTP-DTP-LabProcICE-172 - Comparison RLD flatbelt_VW.pdf WLTP Road Load Family proposal for inclusion in Annex 4 Use vehicle definition for interpolation family as a starting point, but select test vehicles from road load family instead. from WLTP-DTP-LabProcICE-172 - Comparison RLD flatbelt_VW.pdf WLTP Road Load Family, BMW, 10.04.2015

WLTP Road Load Family Conclusion, proposal The family definition and its inclusion in Annex 4 is straight forward by using existing definitions and formulas. Improvement of the wording is welcomed of course. The interpolation range covers to a huge extend the already existing range for an interpolation family and an "add-on" for differences resulting from different engines to be included in one road load family (weight, aerodynamics).  Therefore the range is no extended significantly. Additionally, the concept was validated by testing, which shows a very good accuracy of the calculation method. The Annex 4 taskforce recommends the following: Adopt the family description and add it as a new paragraph 5.7. Adopt the way of including it into the GTR, Annex 4, 4.2.1.1. Adopt the maximum interpolation range of 35% cycle energy. WLTP Road Load Family, BMW, 10.04.2015

from WLTP-DTP-LabProcICE-172 - Comparison RLD flatbelt_VW.pdf WLTP Road Load Family Backup Backup from WLTP-DTP-LabProcICE-172 - Comparison RLD flatbelt_VW.pdf WLTP Road Load Family, BMW, 10.04.2015

from WLTP-DTP-LabProcICE-172 - Comparison RLD flatbelt_VW.pdf WLTP Road Load Family Calculation of road load influences, Annex 7 3.2.3.2.2.4. Calculation of road load for individual vehicles in the CO2 vehicle family 3.2.3.2.2.5. Calculation of cycle energy per phase 3.2.3.2.2.6. Calculation of the CO2 value for an individual vehicle by the CO2 interpolation method Formulas for road load family Formulas for both families Formulas for CO2-family from WLTP-DTP-LabProcICE-172 - Comparison RLD flatbelt_VW.pdf WLTP Road Load Family, BMW, 23.03.2015

CO2-influence of road load family WLTP Road load family CO2-influence of road load family Delta cycle energy WLTC Delta CO2 for an average vehicle Road load family 35%  approx. 5 MJ approx. 38 g/km* CO2 family max. approx. 3.8 MJ max. 30 g/km or 20 % The theoretical CO2-range of the road load family is higher, which is in the order of the additional road load difference resulting from different engine mass (e.g. 4cyl / 6cyl / gasoline / Diesel) or aerodynamic influence (radiator areas). (*) The CO2 range of ~ 38 g/km is a theoretical value, as different engines are included in a road load family, that are obviously in separate CO2-families. CO2-influence derived from GTR Willans factors and confirmed with BMW simulations: Willans for Diesel..gasoline: 161..186 g CO2 / MJ  161..186 g CO2 / 23.3 km * 5 MJ = 35..40 g/km 5 MJ or 35 % as a road load range for the road load family is a reasonable tolerance, which allows to include all similar vehicles into one family. Thus reducing test effort but ensuring that misuse is impossible. WLTP Road Load Family, BMW, 23.03.2015