Working Paper No. WLTP-07-06e
H.S.
7th WLTP IWG meeting, 04. June 2014
Agenda item 5: Status report on
Downscaling / 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
21.05.2014
1
Downscaling, issues to be treated
H.S.
The downscaling procedure is specified in paragraph 7 of
annex 1.
•
One point that needs clarification is related to
paragraph 7.4 of annex 1 “Additional requirements”.
•
The text, that specifies the drive instructions in case
the vehicle cannot follow the trace of the downscaled
cycle does not exclude the activation of a “kick-down”
for automatic transmission vehicles.
•
It is proposed by the TF chairman to add the following
sentence, which was copied from ECE R51:
 External downshifting (for example kickdown) shall be
excluded.
 This proposal needs to be discussed within the TF.
2
Downscaling, issues to be treated
•
H.S.
In addition to that an error in formula 6 of paragraph
7.2.2 of annex 1 needs to be corrected.
 It should read “with i = 1520 to 1724” instead of “with i =
1520 to 1725”.
 Done!
3
Downscaling, issues to be treated
H.S.
•
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 # 5 of WLTP-05-04.
•
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 reanalysed in order to assess this proposal.
4
Downscaling, work done so far
H.S.
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.
5
Downscaling, work done so far
H.S.
•
Second 1566 is the time, at which the maximum power
is required within the cycle for class 3 vehicles.
•
The calculation was performed for 81 vehicles of the
development database. The rated power to kerb mass
ratio of these vehicles varies between 34,1 kW/t to 52
kW/t and includes different transmission designs.
•
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.
6
Downscaling, work done so far
H.S.
•
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.
•
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, but starts at a 3% higher Preq/Prated
values (87% instead of 84%).
7
Downscaling, work done so far
•
The same approach was applied to 105 class 2
vehicles and to 34 class 1 vehicles in the gearshift
prescription development database.
•
The results are shown in figure 1.
H.S.
8
f_DSC vs Preq/Prated, all classes
H.S.
50%
DSC India 3
DSC new proposal, class 3
new proposal, class 2
new proposal, class 1
average class 2 & 3
current GTR, class 3
current GTR, class 2
current GTR, class 1
45%
40%
35%
Downscaling factor
30%
25%
20%
15%
10%
5%
0%
60%
70%
80%
90%
100%
110%
120%
130%
Preq, max, i / Prated
140%
Figure 1
150%
160%
170%
9
Proposal for new r0, a1 and b1 values
H.S.
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: for vehicles with v_max> 105 km/h,
r0 = 0.866, a1 = 0.606, b1 = -0.525.
No downscaling shall be applied for vehicles
with v_max≤ 105 km/h
•
Class 3: for vehicles with v_max> 112 km/h,
r0 = 0.867, a1 = 0.588, b1 = -0.51;
for vehicles with v_max ≤ 112 km/h, r0 = 1.3,
a1 = 0.65, b1 = -0.65.
•
A more simplified proposal, valid for all classes, is
r0 = 0.867, a1 = 0.597, b1 = -0.5175
(yellow curve in figure 11)
10
Downscaling, next steps
H.S.
•
This proposal was sent to the Indian colleagues at
19.05.2014 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.
11
Downscaling using torque meter
method results
H.S.
Another point on the issues list is related to the use of
road load coefficients in the downscaling factor
calculation formulas.
•
# 4 of WLTP-05-04 (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.
12
Gearshifting, current status
•
The gearshift prescriptions for manual transmission
vehicles are specified in annex 2 of the GTR.
•
The following issues are listed in WLTP-05-04 for
further amendments:
H.S.
1. Special gearboxes or auxiliary gearboxes (e.g.
exclusion of “crawler” gears), see OIL # 6 in WLTP05-04.
2. Addition of formulas based on the torque meter
method, see OIL # 7 in WLTP-05-04.
3. Skipping of gears, see OIL # 8 in WLTP-05-04.
•
To point 3 the skipping of the 3 s rule for acceleration
phases, the modification of the safety margin for the
full load power curve and related issues were added. 13
Gearshifting, issues list
•
H.S.
The actual issue list contains the following points:
1. Corrections in the current text (paragraph 3.2),
a. n_max (should be 90% for all gears except highest
gear instead of 120%),
b. Correction of requirements for n_min for 2. gear, (the
current text is insufficient),
c. 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.
14
Gearshifting, issues list
H.S.
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.
6. Additional speed depending safety margin,
7. Assess the exclusion of auxiliary gears (crawler
gears)
15
Gearshifting, current status, next steps
H.S.
•
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.
•
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;
remaining open point: Engine speed limit for gear ngmax
– 1, if gear ngmax is an overdrive.
 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.
16
Gearshifting, current status, next steps
•
H.S.
Ad 1) Corrections in the current text (continued)
 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.
17
Gearshifting, current status, next steps
H.S.
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 3 and top 4 were discussed
together.
 Some group members proposed to find better solutions
for both parameters independent of rated engine speed
(e.g. k*nidle for n_min_drive, k >= 1,2).
 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 considerations in the group.
18
Gearshifting, current status, next steps
H.S.
Ad 2), 3) continued
 In this context the chairman reminded the group that
this new proposal should lead to engine speeds for high
powered vehicles that are still in line with practical use.
 One member mentioned that the maximum torque and
the maximum power of an engine is certified, but not the
full load power curve and expressed the concern that a
certification procedure would be required for the GTR.
 The chairman recommended the consideration of ECE R
85 for the needed requirements.
19
Gearshifting, current status, next steps
•
H.S.
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-DHC09-03).
 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.
20
Gearshifting, current status, next steps
•
H.S.
Ad 5 a) Review gear use at a transition from an
acceleration phase to a cruise phase
 Already in the web/telco was the possibility, to allow
upshifts by two gears at the transition from an
acceleration phase to a cruise phase required, if the
available power would be high enough to ensure
driveability.
 This request was supported and adopted by the group.
 The Japanese colleagues mentioned that it would be
good if this proposal could be supported by actual inuse driving behaviour data and that situations should be
avoided where a downshift would follow within a short
time period after an upshift with a skipped gear.
21
Gearshifting, current status, next steps
•
H.S.
Ad 5 a) Review gear use at a transition from an
acceleration phase to a cruise phase (continued)
 The chairman argued, that this possibility will be
prohibited by the other additional requirements, but
promised to check his database results with respect to
this point and deliver the results prior to the next face to
face meeting.
22
Gearshifting, current status, next steps
•
H.S.
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.
 In addition to that some members argued that phase
indicators for acceleration, cruise and deceleration
would be necessary for clear and robust gear skipping
prescriptions.
23
Gearshifting, current status, next steps
•
H.S.
Ad 5 b) Assess the possibility of skipping of gears during
acceleration phases (continued)
 The chairman argued that he does not see this need but
proposed to use the same criteria for these phases as
were used during the cycle development, if they would
be needed.
 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.
24
Gearshifting, current status, next steps
•
H.S.
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 presented his contribution to this
agenda point and stated that

The current gear shift tool has a 10% margin to full load
and an estimation of inertia for rotating parts of 10%.

The full load margin is based on stationary max
torque/power and cannot account for any transient
response beyond the 10%.
25
Gearshifting, current status, next steps
•
H.S.
Ad 6) Additional speed depending safety margin
(continued)

The inertia estimation compensates to some extent
but not in lower gears.

This means that full load, caused by dynamic
limitations, occurs in the cycle particularly for
engines with turbochargers.

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.
26
Gearshifting, current status, next steps
•
H.S.
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.
27
Gearshifting, current status, next steps
•
H.S.
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 09.
28
Gearshifting, current status, next steps
•
H.S.
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 12.5mph or 20km/h at 75% of rated speed whether
with petrol or diesel engine.
29
Gearshifting, current status, next steps
•
H.S.
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 focussed 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.
30
Gearshifting, current status, next steps
•
H.S.
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 agenda point 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.
31
Gearshift prescriptions using torque
meter method results
H.S.
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.
32
Gear shift family criteria
H.S.
A further point is listed in WLTP-05-04, which should be
added to the gearshift prescriptions:
•
Development of gear shift family criteria, see OIL # 9 in
WLTP-05-04.
•
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.
33