GS/ESC | 21/05/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Coasting in WLTP: BOSCH proposal

Gasoline Systems

Coasting (=Sailing) in WLTP: BOSCH proposalDr. Ansgar ChristGasoline SystemsAdvanced & System Engineering Customer

safe

comfortable

clean andefficient

Invented for life

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GS/ESC | 21/05/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Coasting in WLTP: BOSCH proposal

Gasoline Systems

Motivation Coasting (=Sailing) means driving a vehicle

with open power train, i.e. use natural deceleration, when ICE power demand is low

with engine idling or engine off

Coasting technology (esp. w/ engine off) enables significant CO2

savings in real life “Natural” usage for the driver: Just release gas pedal Coasting occurs in average 20…30% (average vehicle) of the

total driving time

In homologation test cycles a vehicle has to follow the given speed profile as close as possible. Coasting is nearly impossible.

Problem to solve: Provide a simple methodology to quantify real-life Coasting benefit in WLTC which is easily integrated into WLTP GTR?

rolling distance

veh

. sp

eed

Coastingfuel cut off

increased rolling distancedue to eliminated engine drag

rolling distance

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GS/ESC | 21/05/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Coasting in WLTP: BOSCH proposal

Gasoline Systems

BOSCH proposal: General outline

Using same measurement of the vehicle on dyno according WLTP type approval testing conditions

Time resolved recording of fuel consumption necessary

Identify phases with low engine power demands using a power threshold & mark these phases as Coasting phases.

Choose the power threshold so that Coasting time share in cycle matches average Coasting time chare in real life .

Subtract respective zero/idle fuel consumption for identified Coasting phases from the original fuel consumption

Idea: • Coasting occurs whenever power demand to ICE is low!• Account low power phases in test cycle with zero/idle

consumption!

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GS/ESC | 21/05/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Coasting in WLTP: BOSCH proposal

Gasoline Systems

Base Start/Stop shows many low power (<5kW) operating points

With Coasting engine off: shift of low power towards zero-power & zero-engine speed operating points

engine power [kW]

Simulation WLTPcompact class GDI T/C 1.4l, 90kW6-gear MT

en

gin

e s

peed [

rpm

]

Engine operating points with Coasting engine off

probability [-]

pro

babili

ty [

-]

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GS/ESC | 21/05/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Coasting in WLTP: BOSCH proposal

Gasoline Systems

Base Start/Stop shows many low power (<5kW) operating points

With Coasting engine idling: shift of low power towards zero-power & idling-engine speed operating points

engine power [kW]

Simulation WLTPcompact class GDI T/C 1.4l, 90kW6-gear MT

en

gin

e s

peed [

rpm

]

Engine operating points with Coasting engine idling

probability [-]

pro

babili

ty [

-]

5

GS/ESC | 21/05/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Coasting in WLTP: BOSCH proposal

Gasoline Systems

Summary Basic idea of BOSCH proposal:

• Follows the logic of coasting in real life driving• Quantifies coasting fuel consumption benefit on the basis of

original WLTP type approval test measurement

Proposal matches real life benefits No need for complicated cycle modification No need for speed tolerance widening One set value only: Coasting time share

Proposal can be easily integrated into WLTP GTR. No need for additional, special modified test cycle on dyno.

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WLTP Task force “Sailing” should consider BOSCH proposal for further work.