WLTP OIL #6, annex 2, sections 3.2 and 3.3 Determination of engine speeds, calculation of available power

Detailed issue descriptions 2 OIL #6, annex 2, section 3.2, determination of engine speeds  The current text is not precise enough and needs to be amended. OIL #6, annex 2, section 3.3, calculation of available power  The possibility to apply an additional safety margin to the full load power curve at certain engine speed sections was required by India and some vehicle manufacturers.

Determination of engine speeds 3 The proposal for an amended text for section 3.2 of annex 2 of the GTR is as follows: 3.2Determination of engine speeds For each v j < 1 km/h the engine speed shall be set to n idle and it is implied that the vehicle is standing still. The gear lever shall be placed in neutral with the clutch engaged, except one second before beginning an acceleration phase from standstill, where the first gear shall be selected with the clutch disengaged. For each v j ≥ 1 km/h of the cycle trace and each gear i, i = 1 to ng max, the engine speed n i,j shall be calculated using the following equation: n i,j = ndv i × v j (5)

Determination of engine speeds 4 Insert a new section 3.3 and renumber the following sections accordingly: 3.3Determination of possible gears with respect to engine speed boundaries All gears i < ng vmax, for which n min_drive ≤ n i,j ≤ n max_95, and all gears i ≥ ng vmax, for which n min_drive ≤ n i,j ≤ n max (ng vmax ), are possible gears to be used for driving the cycle trace at v j. If a j ≤ 0 and n i,j drops below n idle, n i,j is set to n idle and the clutch should be disengaged.

Determination of engine speeds 5 If a j > 0 and n i,j drops below 1,15 x n idle, n i,j is set to 1,15 x n idle and the clutch should be disengaged. ng vmax is the gear number, in which the maximum vehicle speed is reached. n max_95 is the minimum engine speed, where 95% of rated power is reached. This proposal should be discussed and adopted at WLTP IG #8.

Additional speed depending safety margin 6 The possibility to apply an additional safety margin to the full load power curve at certain engine speed sections was required by India and some vehicle manufacturers. Mr. Malberg presented two alternative proposals as basis for the discussions: 1.Linear power margin, the additional power margin is applied at n idle and linearly approaching zero at n rated. The initial value (at n idle ) is chosen by the manufacturer and recorded. 2.Exponential power margin, the additional power margin is applied between n idle and nT 90 and exponentially approaching zero at n rated.

Additional speed depending safety margin 7 nT 90 is the lowest engine speed at which 90% of maximum torque is reached. The initial margin is chosen by the manufacturer and recorded. The rate of decline is defined in the GTR. It was concluded in the discussions of the TF, that the exponential power margin better reflects the technical / thermodynamic reasons for its necessity and that this approach should be further elaborated. A modified version of this proposal from the chairman, allowing more flexibilities for the manufacturer, was further amended by Annette Feucht with respect to the parameters defining the exponential function (additional margin from n idle to n start, exponential decrease up to n end ).

Additional speed depending safety margin 8 This proposal is as follows: ASM is an additional exponential power safety margin, which may be applied on request of the manufacturer. ASM is fully applied between n idle and n start and exponentially approaching almost 0 at n end as described by the following requirements:  If n ≤ n start, then ASM = ASM 0,  If n > n start, then ASM = ASM 0 x exp(ln(0,005/ASM 0 ) x (n start - n)/(n start - n end )) (7) ASM 0, n start and n end are defined by the manufacturer but must fulfill the following side conditions:  n start ≥ n idle, n end > n start.

Additional speed depending safety margin 9 Equation 6 of annex 2 needs to be amended to: P available i,j = P wot (n i.j ) × (1 - (SM+ASM))(6) This proposal should be added to section 3.4 new. An Excel sheet is attached to this document, which explains the exponential function and gives the possibility to check the influence of parameter variations. It should be considered, that the application of the additional safety margin would lead to an increase of the use of lower gears and thus of the average engine speed.

Additional speed depending safety margin 10 The chairman proposes to use this sheet as basis for the discussions and adoption in the WLTP IG #8.