H.S.H.S.WLTP-08-11

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01.11.2014

OIL #6, annex 2, section 2

Use of the gearbox, required data

H.S.H.S.Detailed issue descriptions

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• OIL #6, use of the gearbox, required data can be split into the following subsections:

1. the definition of nmin_drive should be modified in order to make it more appropriate for modern engines and to make manipulations more difficult.

2. nmax needs to be added to section 2, required data and needs to be amended, because the current definition is not appropriate for low powered vehicles.

3. section 2 (i), Pnormwot(nnorm i, j) should be replaced by Pwot(n i, j), since there is no need for the normalisation.

H.S.H.S.Definition of nmin_drive

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• The issue of an amendment of nmin_drive is by far the most complex and controversely discussed issue.

• The chairman prepared WLTP-GS-TF-13 for the further discussion and distributed it at 09.08.2014. This document compared 4 different proposals for modified nmin_drive determination methods.

• Based on his assessment he proposed to continue the further discussion with proposals 3 and 4 of this paper.

• But the group should of course get time to assess WLTP-GS-TF-13.

H.S.H.S.Definition of nmin_drive

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• In the meantime one group member came up with an additional proposal based on the engine speed in the highest gear at the maximum cycle speed:

nmin_drive = nidle + k * ndv_ngmax * 131,3

• This proposal is simple to calculate, independent from engine rated power and considering drivetrain layout.

• It was agreed that this proposal should be included in the further investigations.

• The GS-TF asks the WLTP IG for an extension of the time schedule for this issue in order to allow more detailed discussions and assessments.

• A final amendment proposal from the group should be ready till end of February 2015 latest.

H.S.H.S.Definition of nmin_drive

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• But apart from this, the text in annex 2 of the GTR needs to be amended with respect to nmin_drive for clarity reasons. Section 2 required data, bullet point (e) should be amended as follows:

(e) nmin _drive, minimum engine speed when the vehicle is in motion

for ngear = 1, nmin_drive = nidle,

for ngear = 2, nmin_drive = 0,9 x nidle,

for ngear > 2, nmin_drive is determined by :

nmin_drive = n_idle + 0.125 ×(s-nidle ) (1)

Higher values may be used if requested by the manufacturer.

H.S.H.S.Definition of nmin_drive

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• This proposal is already implemented in WLTP-08-15.

• It should be discussed and adopted at WLTP IG #8.

H.S.H.S.Definition of nmax

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• The current definition in the GTR is nmax = 1,2*(nrated – nidle).

• India requested to come back to the previous definition nmax = 0,9*(nrated – nidle)+nidle, if ng < ngvmax.

• A new proposal for nmax was introduced by the chairman:

• If ng < ngvmax. nmax is the minimum engine speed, where 95% of rated power is reached, else nmax is limited by v_max of the WLTC. ngvmax is the gear number, in which the maximum vehicle speed is reached.

• Figure 1 shows a comparison of the values requested by India (n_max_old) and the new proposal by the chairman.

H.S.H.S.

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n_m

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Definition of nmax

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H.S.H.S.Definition of nmax

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• The chairman’s proposal was discussed and adopted by the group. It is already implemented in WLTP-08-15.

• This proposal will be brought to the WLTP IG in order to be discussed and adopted at meeting #8.

H.S.H.S.Pnormwot(nnorm i, j) -> Pwot(ni, j)

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• During the development process of the gearshift prescriptions normalised full load power curves versus normalised engine speeds had to be used in order to assess the results for different engine and powertrain combinations.

• For a particular vehicle under test the use of normalised curves is an unnecessary burden, because the current prescriptions in annex 2 require a denormalisation.

• Therefore the group proposes to amend the text in annex 2 accordingly.

• It is already implemented in WLTP-08-15.

• This proposal should be adopted at WLTP IG #8.