WLTP-10-11e 1 By H. Steven Status report about the work of the gearshift issues task force

Progress made since WLTP IGM #9 2 The task force discussed and adopted a series of improvements for the text in sections 1 to 4 of annex 2.  In section 1.1 was specified that annex 2 is dedicated to manual transmissions only.  The specifications for n min_drive for the 2. gear were improved in section 2 (e).  The specifications for ng vmax were improved in section 2 (i).  A specification for n max was added in section 2 (l).  The specifications for P wot (n) was improved in section 2 (m).

Progress made since WLTP IGM #9 3  The additional requirements for corrections and/or modifications of gear use (section 4) were restructured and improved.  The different requirements were brought into a more logical rank order and some of them were described more precise. These modifications were already presented at the last meeting of the drafting group (at in Brussels) and implemented in the latest GTR draft.

Still open issues 4 The following issues are still under discussion:  Amendment of n min_drive requirements.  Crawler gear specifications. The status of the discussions in the group is reported in the following slides.

Amendment of n min_drive requirements 5 Henrik Malberg presented an acceleration potential based approach at the last face to face meeting at , which seemed to be promising for the group (VCC proposal). Christoph Lueginger presented a proposal which was elaborated by BMW. This proposal was not intended as counter proposal but as fallback proposal in case the acceleration potential based proposal could not reach the goal. In the meantime the VCC proposal was assessed by the convenor by applying it to 87 different vehicle configurations from the development database, covering all 3 vehicle classes.

Amendment of n min_drive requirements 6 Since the acceleration potential is tuned by the maximum torque to mass ratio in the VCC proposal, significant differences were found between Diesel and Petrol vehicles. The conclusion of the convenor was, that Petrol vehicles get a bonus and Diesel vehicles a malus with this tuning method and he proposed to replace the max torque to mass ratio by max power to mass ratio. At least for his vehicle sample he could show, that one could get results with this modified tuning system, that would be quite close to those, attained by the current n min_drive definition.

Amendment of n min_drive requirements 7 But Henrik Malberg argued, that a power to mass based tuning method would favour Diesel vehicles too much. And he asked for more time for assessment and example calculations. The group agreed, that the acceleration potential based approach for n min_drive will be the best solution, but it needs to be clarified in a next step, what tuning method should be used. This would have required more time than was left for the elaboration of a proposal for IWG meeting #10.

Amendment of n min_drive requirements 8 As a consequence there was no chance left to deliver a proposal in due time to the WLTP IWG for meeting #10 for adoption. The group agreed that the convenor should describe this situation in his status report for meeting #10 and should ask the IWG for an extension of the deadline till meeting #11 in Geneva.

Crawler gear specifications 9 At the last face to face meeting Nick Arden introduced a specification proposal, which is based on a toe away criterion and on two transmission design criteria for the gear ratio spread between 1. gear and the gear, in which the maximum vehicle speed is reached and 2. gear and the gear, in which the maximum vehicle speed is reached. This proposal was elaborated by Nick Arden and the convenor. The two transmission design criteria are introduced in order to prevent misuse of the crawler gear prescriptions. This proposal was accepted by all group members except the Japanese colleagues. They had objections and asked for more assessment time.

Crawler gear specifications 10 In the meantime the Japanese colleagues sent examples of vehicle configurations to Nick Arden and the convenor, which have a crawler gear, but would not qualify, when applying the proposal criteria. These examples were assessed by the convenor and he made a proposal for an improvement of the requirements by applying a correction factor on the gear ratio spread calculation. This factor is the ratio between a v max value, purely based on the driving resistance power (P res = P rated ) and transmission design independent and the vehicle speed at rated engine speed for that gear, in which the maximum vehicle speed for the given transmission design is reached.

Crawler gear specifications 11 The application of this correction factor to the examples, delivered by the Japanese colleagues, let qualify three out of six vehicles, that would not qualify before. The Japanese colleagues promised to assess this new proposal. By the end of March the convenor got an from the Japanese colleagues, in which they stated, that the latest proposal (Arden/Steven) could work. But they also expressed some concerns with the methodology and gave an outline for a counter proposal.

Crawler gear specifications 12 This is based on two criteria, 1.(GTM – UM)/rated power > threshold x, 2.Duration of the use of 1st gear at the beginning of the high phase (highest acceleration within the cycle) < threshold y. This indicates that 2nd gear has enough capability at low speeds and high accelerations. GTM = Gross Train Mass = Gross Vehicle Mass + max trailer mass. UM is the unladen mass of the vehicle. Of course, there was not enough time for an assessment of this counter proposal before IWG #10.

Crawler gear specifications 13 As a consequence there was no chance to deliver a proposal in due time to the WLTP IWG for meeting #10 for adoption. The group agreed that the convenor should describe this situation in his status report for meeting #10 and should ask the IWG for an extension of the deadline till meeting #11 in Geneva.

Gearshift issues task force 14 This concludes the status report about the work of the gearshift issues task force.