WLTP: Progress report on downscaling and gearshifting

Working Paper No. WLTP-09-07e
H.S.
9th WLTP IG meeting, 14. January 2015
Agenda item 5: Progress report on
Downscaling / Gearshifting (OIL #4-9)
by H. Steven
06.01.2015
1
Downscaling
H.S.
•
The downscaling procedure is specified in GTR 15 in
paragraph 7 of annex 1.
•
The method as such is agreed, but paragraph 7.3
“Determination of the downscaling factor” needed to
be amended.
•
India requested 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.
•
Meanwhile additional analysis work was performed by
the task force and an amendment proposal was
presented to the IG at meeting #8 (see WLTP-08-10e).
2
Downscaling
•
H.S.
This proposal was adopted at WLTP IG #8, so that the
work is finalised and OIL #5 can be closed.
3
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.
•
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).
 This issue should be dealt with in the annex 4 task
force in conjunction with OIL #16.
4
Gearshifting, issues list
•
The gearshift prescriptions for manual transmission
vehicles are specified in annex 2 of the GTR.
•
The actual issue list contains the following points:
H.S.
1. OIL #6, annex 2, section 2, Use of the gearbox,
required data,
2. OIL #6, annex 2, section 2, Use of the gearbox,
auxiliary gearboxes, exception of crawler gears,
3. OIL #6, annex 2, sections 3.2 and 3.3, Determination
of engine speeds, calculation of available power
5
Use of gearbox, required data
•
H.S.
OIL #6-1, 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.
6
Definition of nmin_drive
H.S.
•
The issue of an amendment of nmin_drive is by far the
most complex and controversely discussed issue.
•
The current discussion is based on 3 different
proposals, but since the 3rd proposal was delivered
rather late to the task force (shortly before WLTP IG
#8), so that the task force of course needs some time
to assess the proposals.
•
Therefore the GS-TF asked the WLTP IG at meeting #8
for an extension of the time schedule for this issue in
order to allow more detailed discussions and
assessments.
•
The task force should work on an amendment
proposal to be ready for adoption at WLTP IG #10.
7
Definition of nmax
H.S.
•
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 vmax of the WLTC. ngvmax is the gear number,
in which the maximum vehicle speed is reached.
•
This proposal was adopted by the task force and
presented to the WLTP IG at meeting #8.
•
The proposal was adopted by the IG.
8
Pnormwot(nnorm i, j) -> Pwot(ni, j)
H.S.
•
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 task force proposed to amend the text in
annex 2 accordingly.
•
This proposal was presented at WLTP IG #8 and
adopted.
9
Auxiliary gearboxes, exception of
crawler gears
•
H.S.
OIL #6-2, use of the gearbox, required data can be split
into the following subsections:
1. Add requirements, how to deal with vehicles with a
two range transmission (low and high),
2. Introduce the possibility to exclude crawler gears
from the gear use calculation.
•
With respect to 1. the task force proposed to add a
new subsection 1.4 to section 1 of annex 1 with text
that excludes all gear ranges not normally used for on
road operation.
•
This proposal was adopted at WLTP IG #8, but the
wording needs to be improved regarding “range” (B.
Coleman, Drafting Coordinator).
10
Exclusion of auxiliary gears
H.S.
•
The issue to exclude crawler gears from the gear use
calculation is still under discussion.
•
The crawler gear is an occasional use gear for heavily
laden conditions, steep hill starts or maintaining a very
slow controlled speed when laden.
•
A crawler gear is very similar to the ‘low range’ transfer
boxes used on off road vehicles (see issue 1. on
previous slide).
•
The main problem is to define delimination criteria for
the crawler gears and the 1. gear for normal operation,
that are performance based rather than design based.
•
Special attendance has to be drawn to prohibit, that
the requirements enable to skip the 1. gear for high
powered sports cars.
11
Exclusion of auxiliary gears
H.S.
•
Proposals from Nick Arden and the Japanese
colleagues are currently discussed in the task force,
but the task force concluded that more time for further
discussions is needed.
•
The WLTP IG extended the timeframe at its meeting #8
till WLTP IG #10.
12
OIL #6, annex 2, section 3.2
•
H.S.
OIL #6, annex 2, section 3.2, determination of engine
speeds
 The current text is not precise enough and needs to
be amended.
•
An improved text was developed by the task force and
presented at WLTP IG #8.
•
The text amendments were adopted by WLTP IG at ist
meeting #8.
13
OIL #6, annex 2, section 3.3
•
H.S.
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.
•
A modified version of the initial proposal made by
Henrik Malberg was adopted in the task force and
presented at WLTP IG #8.
•
This proposal was adopted by the WLTP IG.
14
OIL #8, review 3 s rule for acc phases
H.S.
•
This issue was requested by a N1 manufacturer,
because the 3 s rule could lead to too high engine
speeds for vehicles with „short“ transmissions,
especially for the 1. gear.
•
The task force discussed this issue extensively and
came up with the proposal to change the 3 s rule to a 2
s rule already in an early stage of the discussions,
because this change could ease the prescriptions
significantly with respect to other requirements (e.g.
skipping of gears) and does not lead to significant
changes in the engine speed distributions.
•
This proposal was presented at the WLTP IG #8 and
adopted.
15
Further improvements of annex 2
H.S.
•
But apart from this, the text in annex 2 of the GTR
needed to be amended for clarity reasons.
•
These amendments were elaborated by the task force
leader and presented to the WLTP IG at meeting #8
(see WLTP-08-14e rev1).
•
These amendments were adopted by the WLTP IG.
16
Gearshift prescriptions using torque
meter method results
H.S.
Another point on the issues list (OIL #7) 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).
 This issue should be dealt with in the annex 4 task
force in conjunction with OIL #16.
17
Gear shift family criteria
H.S.
A further point is listed in the OIL: Development of gear
shift family criteria, see OIL # 9
•
This issue was discussed in the task force with the
conclusion, that it is not necessary and thus can be
deleted from the OIL.
•
This proposal was presented to the WLTP IG at
meeting #8 and was adopted.
18
Next meeting of the task force
•
H.S.
The next meeting of the task force is scheduled for 4th
February 2015.
19