Wind tunnel method as an alternative to road load determination method under GTR No. 15 (WLTP)
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Reference Number: WLTP-11-12
Origin: BMW and UTAC
Date: 3 June 2015
Related Documents:
WLTP-12-14 | GTR No. 15 (WLTP) Phase 1b: Wind tunnel method and chassis dyno prescriptions (revision 2)
Worldwide Harmonized Light Vehicles Emissions Test Procedure | Session 11 | 9-10 Jun 2015

Progress report on RLD issues was given by R. Cuelenaere (WLTP-11-11e).

OIL # 18: Wind tunnel method as alternative RLD method: Updated GTR proposal (WLTP-11-12e), incl. tolerances, was reviewed by the task force and was adopted by IWG WLTP. Drafted text for the wind tunnel method will be finished in the next Drafting Subgroup meeting. Flat Belt /dyno part will be developed further; proposal expected for adoption at IWG meeting #12.

OIL # 48: Correction Algorithms (Dyno load setting (2.7)) Proposal on time gaps between warm up and coast down by Audi (WLTP-10-19-rev1e) was accepted by the task force and adopted by the IWG. Drafted text is provided to the DC. On request of the RLD TF coordinator the Chair clarified that no further RLD related issues from the COM proposal for correction algorithms (WLTP-08-38e) will be put on the RLD TF agenda for Phase 1B.

OIL# 1b_5: Manufacturer’s responsibility for accuracy of road load specifications: Proposal was presented by Japan (WLTP-11-13e). Chair welcomed the more generic approach in phase 1b of WLTP, since in-use-provisions are foreseen in phase 2. EU Com welcomed the proposal for phase 1b, but stressed the importance of a specification of tolerances within WLTP phase 2. Proposal was discussed and adopted by the IWG with the following changes: “specification” —> “coefficients”, “should” —> “shall”.

OICA remarked the lacking alignment of specified tolerances in Annex 4 and will develop an amendment for review in the RLD TF and SG Drafting (no IWG document required).

RLD TF will provide the Japanese overview matrix of applied Annex 4 tolerances for information purposes in advance of IWG meeting #12.

OIL # 11, 13: Onboard-anemometry / wind conditions: Draft GTR proposal (WLTP-11-14e) was presented by Ford. Discussion arose about referring to SAE or ISO standards. Chair recommended a standalone text in the GTR with explanation in the technical report (note: the issue has been reported to GRPE on June 11th and guidance was requested. The UN Secretariat informed about the ongoing general discussions on WP.29 level and offered to prepare the discussions with the SAE representative). T&E asked for the need of other mounting positions. Ford will provide background to the task force.

Proposed deletion of regional option of more open wind conditions was adopted by the IWG. DC will change the GTR accordingly. OIL #11 is closed.

OIL # 4, 7, 14- 16, 20: Torque meter method (incl. road load curve correction/chassis dyno load setting). Validation results presented by Ford (WLTP-11-15e) showed good equivalence, which was confirmed as sufficient by WLTP IWG. Rob Cuelenaere explained the draft gtr proposal (WLTP-11-16e) and outlined the approaches to solve the remaining OIL items. WLTP IWG agreed to the approaches. TF will further work on the text and involve the SG Drafting in advance before the meeting #12.

EU Com raised concerns about the chain of tolerances in getting road load coefficients backwards out of the road measurement and followed dyno setting. TF will handle that issue within a dedicated torque meter meeting. Basic approach is accepted by the IWG.

OIL# 17: Default road load parameters.: Combined progress report by RDW/Daimler (WLTP-11-17e) incl. initial draft GTR proposals for the so called Road Load Matrix Family. TF Leader appreciated the constructive work in the task force. Chair welcomed the progress on this open issue.

EU Com appreciated the summarizing overview of methods (table page 31) and recommended inclusion in GTR (technical report). Approach for selection of a representative test vehicle was supported by IWG.

Compromise proposal by TF on the necessary amount of safety margin was explained. T&E requested greater margin. EU Com will review the safety margin in EU-WLTP. Japan had no reservation as long as the method is restricted to heavy cars as proposed. Political decision is expected. Taskforce is asked to prepare a decision paper for gaining feedback of the CP’s until end of June.

OICA will provide a proposal for an adapted range of CO2 for a road load matrix family (Bill Coleman).

OIL # 1b_3: Tyre selection status report was given by K. Steininger. Data from ETRTO will be further investigated. EU will consider circulating a proposal well in advance before meeting#12.

OIL# 10: Wind tunnel for combined approach: editorial updated draft document (WLTP-11-18e) was already adopted in meeting#10. OIL#10 is closed.