H.S.H.S.Working Paper No. WLTP-07-06e short

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Agenda item 5: Status report onDownscaling / Gearshifting (OIL #4-9)

Points that are resolved in the TFs are written in green colour.Points that still need further considerations are written in red colour.

by H. Steven

03.06.2014

7th WLTP IG meeting, 04. June 2014

H.S.H.S.Downscaling, issues to be treated

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• The downscaling method as such is agreed, but paragraph 7.3 “Determination of the downscaling factor” needs to be amended.

• India requests modifications of the calculation parameter/coefficients r0, a1 and b1 and made already a proposal for amendments (see WLTP-DHC-18-05). This issue is related to OIL # 5.

• Calculations based on the Indian amendment proposal were performed for a series of class 3 vehicles.

• In addition to that the database used for the development of the downscaling method was re-analysed in order to assess this proposal.

H.S.H.S.Downscaling, work done so far

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The following approach was chosen and applied to class 3 vehicles.

• The downscaling method uses the ratio between the maximum required power of the cycle phases where the downscaling is to be applied and the rated power of the vehicle.

• This ratio is independent of the transmission design, which is necessary in order to make the method applicable for any kind of transmission.

• But in order to better consider the influence of the transmission design, the necessary downscaling factor was related to the power available in second 1566 of the WLTC instead of rated power.

H.S.H.S.Downscaling, work done so far

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• Second 1566 is the time, at which the maximum power is required within the cycle for class 3 vehicles.

• As expected, the correlation is much better than for rated power.

• The correlation between Preq/Pavailable and Preq/Prated was used in order to re-establish the relationship with Preq/Prated.

• A significant number of vehicles (14 of 81) have ratios that are further away from the regression curve.

• For these vehicles it can be expected, that f_DSC based on the regression line will not be sufficient, especially, when the wot percentage is considered as additional requirement.

H.S.H.S.Downscaling, work done so far

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• Therefore the average between the regression curve and the upper envelope curve is proposed by the chairman as compromise.

• This results in a f_DSC curve, that is close to the Indian proposal.

• The same approach was applied to class 2 vehicles and to class 1 vehicles in the gearshift prescription development database.

• The results lead to the following amended values for the coefficients r0, a1 and b1.

H.S.H.S.Proposal for new r0, a1 and b1 values

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The calculation parameter/coefficients r0, a1 and b1 are determined as follows:

• Class 1: r0 = 0.978, a1 = 0.680, b1 = -0.665

• Class 2: r0 = 0.866, a1 = 0.606, b1 = -0.525.

• Class 3: r0 = 0.867, a1 = 0.588, b1 = -0.51;

• A more simplified proposal, valid for all classes, is r0 = 0.867, a1 = 0.597, b1 = -0.5175

H.S.H.S.Downscaling, next steps

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• This proposal was sent to the Indian colleagues for comments and assessment.

• After the consultations with the Indian colleagues, the proposal will be sent to other stakeholders within the WLTP IG for further consultations.

• The final proposal will be sent to the WLTP IG in due time prior to meeting 8 for decision.

H.S.H.S.Downscaling using torque meter

method results

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Another point on the issues list is related to the use of road load coefficients in the downscaling factor calculation formulas.

• OIL # 4 (Calculation parameter/coefficients for torque meter method):

The problem was clarified between Japan and HS (coast down method delivers f0, f1 and f2, torque meter method delivers C0, C1 and C2).

The discussions with test bench and calculation experts are still ongoing. A deadline for a solution cannot be fixed yet.

H.S.H.S.Gearshifting, issues list

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• The gearshift prescriptions for manual transmission vehicles are specified in annex 2 of the GTR.

• The actual issue list contains the following points:

1. Corrections in the current text (paragraph 3.2),

2. Specification of rated engine speed in case of a Prated plateau,

3. Amendment of the definition of n_min_drive,

4. Review 3 s rule for acceleration phases,

5.

a. Review gear use at a transition from an acceleration phase to a cruise phase,

b. Assess the possibility of skipping of gears during acceleration phases.

H.S.H.S.Gearshifting, issues list

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6. Additional speed depending safety margin,

7. Assess the exclusion of auxiliary gears (crawler gears)

• The task force had a web/telco at 20.03.2014 and a face to face meeting at 08.05.2014 in Brussels with the participation of the Japanese colleagues via web/telco.

• JRC and the Indian colleagues were informed about the results of the discussions by the meeting minutes.

H.S.H.S.Gearshifting, current status, next steps

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• Ad 1) Corrections in the current text (paragraph 3.2) n_max (should be 90% for all gears except highest gear

instead of 120%) was agreed and accepted;

Correction of requirements for n_min for 2. gear, (the current text is insufficient). The chairman will prepare an amendment till end of June 2014.

Point (d) of the additional requirements for corrections and/or modifications of gear use (see para 4 of annex 2 of the GTR) is unnecessary and can be skipped, because it is covered by point (e). The rank order of the other points in the calculation tool is: (b), (c), (e), (f), (g), (a). The text in the GTR should be rearranged accordingly.

The chairman will prepare an amendment till end of June 2014.

H.S.H.S.Gearshifting, current status, next steps

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Ad 2), 3) Specification of nrated in case of a Prated plateau,

Amendment of the definition of n_min_drive Since this issue is mainly related to the specification of

n_min_drive and n_max, top 2 and top 3 were discussed together.

Some group members proposed to find better solutions for both parameters independent of rated engine speed.

In this case point 2) becomes unnecessary.

The group agreed that further investigations and more time would be necessary in order to find a robust solution. One member of the group volunteered to prepare a proposal by end of June 2014 as basis for further consideration in the group.

H.S.H.S.Gearshifting, current status, next steps

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• Ad 4) Review 3 s rule for acceleration phases The Japanese colleagues argued, that a time period > 1

s in a specific gear is necessary from the view points of repeatability and reproducibility and because the time tolerance for a gearshift is +/- 1 s (Annex 6, 1.2.6.5.1.2).

Therefore they recommended to replace the 3 s rule by a 2 s rule, as originally proposed by Japan (WLTP-DHC-09-03).

One colleague expressed some concerns with respect to the 1. Gear and Ford’s in-use driving behaviour data, but agreed to go ahead with this proposal.

The other group members supported the Japanese proposal.

H.S.H.S.Gearshifting, current status, next steps

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• Ad 5 a) Review gear use at a transition from an acceleration phase to a cruise phase

Already in the web/telco was required to allow upshifts by two gears at the transition from an acceleration phase to a cruise phase, if the available power would be high enough to ensure driveability.

This request was supported and adopted by the group.

H.S.H.S.Gearshifting, current status, next steps

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• Ad 5 b) Assess the possibility of skipping of gears during acceleration phases

The Japanese colleagues questioned that the possibility to skip a gear during an acceleration phase would be necessary with the 2 s rule.

This issue is also linked to the definition of n_min_drive. Upshifts by two gears would be avoided, if the n_min_drive values would be high enough.

The chairman promised to perform calculations with his database applying the 2 s rule and the possibility to skip gears and to deliver the results for further discussions prior to the next face to face meeting.

H.S.H.S.Gearshifting, current status, next steps

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• Ad 6) Additional speed depending safety margin This request was raised by vehicle manufacturers from

India and Europe with regard to downsized, high pressure turbocharged engines.

In the current tool such measure is already foreseen with the additional margin fully applied at idling speed and linearly reduced to 0 at rated speed.

One group member illustrated the problem in more detail by his presentation and stated that

- The target is to find a general method to characterize dynamically available torque for turbocharged engines.

The colleague presented alternatives in order to solve the problem and illustrated and discussed these alternatives based on his further slides.

H.S.H.S.Gearshifting, current status, next steps

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• Ad 6) Additional speed depending safety margin (continued) The conclusion of the group was that engine type

specific solutions would be required, if the problem would be solved by an approximation of the dynamic torque response and that more general solutions (like an additional safety margin for low engine speeds) bare the risk, that their effectiveness for different engine designs is different.

After intensive discussions the group agreed on the following proposal as basis for further considerations:

- The manufacturer can require and define an additional safety margin, which is fully applied at idling speed and linearly reduced to 0 at rated speed. This extra margin needs to be documented.

H.S.H.S.Gearshifting, current status, next steps

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• Ad 6) Additional speed depending safety margin (continued) Some members required the possibility to propose

alternative solutions till the end of June 2014.

It needs to be checked whether there could be a goal conflict with OBD requirements.

Also possible interactions with n_min_drive need to be checked.

This point might require more time, so that it could be necessary to extend the deadline for a proposal till WLTP IG #9.

H.S.H.S.Gearshifting, current status, next steps

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• Ad 7) Assess the exclusion of auxiliary gears The proposal from Ford was used as basis for the

discussion.

It consists of six different criteria. Three of them are technical requirements, the other three supportive.

The technical requirements are:

a. The vehicle can pull away in 1st gear at 50% GTM at 20% incline within 4.0 s.

b. The vehicle cannot pull away in 1st gear at GTM on 20% incline within 4.0 s.

c. The vehicle when in crawler gear has maximum speed of 20 km/h at 75% of rated engine speed.

H.S.H.S.Gearshifting, current status, next steps

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• Ad 7) (continued) This proposal was discussed and the group at first

agreed that the supportive requirements should be disregarded.

The requirement c. was adversatively discussed. Therefore the group focused in the further discussion on modifications of requirements a and b.

The following proposal was made, which shall be used for further considerations:

The first gear is a crawler gear and disregarded for the gear use calculation, if the vehicle can pull away in second gear at 20% incline within 4.0 s with test mass high but not with gross vehicle mass.

The Japanese colleagues agreed but required the possibility to work on a counter proposal.

H.S.H.S.Gearshifting, current status, next steps

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• Ad 7) (continued) The rest of the group shall consider, whether this

proposal could be misused by very high powered vehicles.

In the context of this item it needs to be checked, whether the current GTR text excludes the low transmission range for vehicles with low and high range transmissions, where the high range is dedicated to on road operation and the low range is dedicated to off road operation.

If not, the GTR needs to be amended accordingly. The group supported this proposal.

The discussion will be continued at the next face to face meeting based on further proposals from the group.

H.S.H.S.Gearshift prescriptions using torque

meter method results

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Another point on the issues list is related to the use of road load coefficients in the gearshift calculation formulas.

• Add calculation formulas based on road load values from the torque meter method

The problem was clarified between Japan and HS (coast down method delivers f0, f1 and f2, torque meter method delivers C0, C1 and C2).

The discussions with test bench and calculation experts are still ongoing. A deadline for a solution cannot be fixed yet.

H.S.H.S.Gear shift family criteria

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A further point is listed in the OIL, which should be added to the gearshift prescriptions:

• Development of gear shift family criteria, see OIL # 9.

• For this point the GP TF will be co-chaired by Japan and HS.

• The necessary steps for this issue will be drafted after preparatory discussions with Japan.