Starting notes for Annex 4 Phase2a Issues WLTP-14-20e Starting notes for Annex 4 Phase2a Issues Japan

Starting note for Correction for the dynamometer roller radius Issue: Under Phase-1b the general approach was agreed, as well as the compromise proposal on the actual correction factors. It was decided that a review of the correction factors would be part of the WLTP Phase-2a working items. The guideline of determination of c1 and c2 values will be discussed. 6.6.3. of Annex 4 General approach alternative conservative equation The manufacturer and responsible authority shall agree on the factors c1 and c2 to be used, based on correlation test evidence provided by the manufacturer for the range of tyre characteristics intended to be tested on the chassis dynamometer. c1 = 1.0 c2 = 0.2 Proposed steps： Discuss in conjunction with alternative roadload determination method (proposed by Japan).

Starting note for Correction for Additional cooling fan Issue: There is requirement that allows manufacture to use additional cooling fan. For the vehicle whose engine is installed, for example in rear compartment, the additional cooling fan is necessary in order to apply appropriate cooling. Proposal： “If manufacturer can show that during field operation the vehicle　receives additional cooling, and that such additional cooling is needed to provide a representative test, additional fans may be used, if approved in advance by Responsible Authority.”

Starting note for Correction for Alternative road load determination process Issue: According to current GTR, there are two main methods to determined roadload which are (a) actual coastdown test and (b) wind tunnel + Flatbelt (or chassis dyno) method. When we use the combined approach to derive individual vehicle roadload, delta wind tunnel ( i.e. dCdA) can be used, however there is no description which allows to use delta flatbelt (or dyno) to derive individual vehicle’s roadload. Measuring roadload Coastdown Wind tunnel Flatbelt (or dyno) + or Combined approach or Roadload family Vehicle individual＝ 𝑓 0 + 𝑓 1 ×𝑣+ 𝑓 2 × 𝑣 2 ⊿Weight ⊿RRC ⊿CdA (=⊿Wind tunnel) ⊿Flatbelt (or ⊿dyno) Proposal Discuss an alternative method which allows to use “delta” of Flatbelt or chassis dyno measurement results in order to calculate roadload for individual vehicles.

1. Measuring base model road load by coastdown or Wind tunnel method. Starting note for Correction for Alternative road load determination process 1. Measuring base model road load by coastdown or Wind tunnel method. Base model road load = Base model rolling resistance + Base model aerodynamics 2. Measuring the difference of rolling resistance of base model and individual vehicles on flat belt or chassis dynamometer Rolling resistance difference = Individual vehicle’s rolling resistance - Base model rolling resistance 3. Calculating individual vehicle’s road load Individual vehicle’s road load = Base model road load + Rolling resistance difference