WLTP-11-5e Status report about the work of the gearshift issues task force

Progress made since WLTP IGM #10 2 After IWG #10 the following issues remained on the OIL with the task to develop and prepare proposals for adoption for IWG #11 in June in Geneva: 1.Crawler gear prescriptions, 2.Amendment of n_min_drive definition. For both issues information and analysis results between involved members of the TF was exchanged via or telephone calls. A face to face meeting took place at in Brussels. The status of the work can be summarised as follows:

Crawler gear prescriptions 3 There was a proposal from Nick Arden and the chairman on the table since April 2015 which incorporated solutions for concerns of the Japanese colleagues. This proposal is based on gear spread ratios between the gear, in which the maximum speed is reached, and the 1 st and the 2 nd gear and a toe away criterion. This proposal was supported by the other TF members except the Japanese colleagues, who came up with a counter proposal.

Crawler gear prescriptions 4 This counter proposal is based on  (GTM – UM)/Prated in order to eliminate the high power sports cars and  Duration of 1st gear in high-phase at maximum acceleration, when starting from stop to be less than YY second in order to indicate that 2nd gear has enough capability at low speed and high acceleration range. This proposal was assessed by Nick Arden and the chairman. The latter expressed concerns about the robustness and the safeguard against misuse and recommended to adopt the Arden/Steven proposal.

Crawler gear prescriptions 5 The Japanese colleagues pointed out during this meeting that Japan changed its mind and the new position was, to skip any crawler gear exception for the gearshift calculation and to start always with the lowest gear. Nick Arden reacted to this statement by explaining again in detail the advantages, which could be gained for fuel economy and CO 2 emission reduction by applying crawler gears in future vehicle concepts/designs. After this, the chairman asked the Japanese colleagues again, whether there would be a chance to support the Arden/Steven proposal.

Crawler gear prescriptions 6 The Japanese colleagues asked for a short break for internal discussions and after this break, they confirmed their support for the Arden/Steven proposal. The chairman concluded that the proposal is now adopted by the TF and that he will prepare a text proposal for the GTR and present this to WLTP IWG #11 for adoption (see WLTP-11-6e).

Amendment of n min_drive definition 7 The chairman started the discussion about this agenda point by presenting WLTP-GS-TF-28, which summarises the different proposals, currently discussed. In this presentation the average engine speeds of his example database (128 vehicles ranging from 15 kW/t up to 317 kW/t pmr) resulting from the current n_min_drive definition and the different proposals for an amendment were compared for a vehicle speed range between 17,5 km/h and 62,5 km/h with corresponding average engine speeds for manual transmission vehicles in the WLTP in-use database.

Amendment of n min_drive definition 8 The following amendment proposals were included: 1.Current n min_drive = n idle + 0,125*(s – n idle ), 2.VCC old, based on a required acceleration = f(Tmr): a req = 8*T max /m test + 0,8, 3.Counter proposal (same approach, but a req = f(Pmr): a req = 40*(P max /m test ) *(P max /m test ) + 0,4 4.BMW (fallback) proposal: Petrol engines: n min_drive = -0,025*capacity , Diesel engines: n min_drive = -0,037*capacity VCC new (combination of 2. and 3.): a req = 6*T max /m test + 15*P max /m test + 0,4

Amendment of n min_drive definition 9 The chairman pointed out that the new VCC proposal shows the best fit with the in-use data and consequently asked the participants whether the group could go ahead with this proposal. In this context he stated, that he would be able to prepare a report for the IWG #11 with a GTR text describing this amendment proposal but with the coefficients in the calculation formula above in square brackets, so that there would be still time left for further improvements after the IWG #11. If this would not be the case, he would have to report to the IWG, that the group would still need more time and no proposal for adoption would be available for IWG #11.

Amendment of n min_drive definition 10 Unfortunately, the group could not agree to go ahead with the new VCC proposal and a lengthy discussion took place, in which diverging requirements were expressed by some members of the group. The information and analysis results exchange was continued after the meeting at Based on the results it can be foreseen that the TF will be able to agree on a common proposal by the end of June 2015, so that a proposal for adoption at IWG #12 will be delivered in due time. The chairman asks the IWG to allow the additional enlargement of the timescale.

Additional discussion points 11 The following additional points were discussed in the TF and the chairman was asked to bring them to the IWG: 1.Transfer the vehicle classification borderlines from P rated /m kerb to P rated /m test, 2.Add checksums for cycle identification and add the request to report detailed information about downscaling to annex 1, 3.Add calculation of average gear to annex 2. Further details are provided in WLTP-11-8e.

Gearshift issues task force 12 This concludes the status report about the work of the gearshift issues task force.