Lotus AVTTM System for Advanced Diesel Combustion

Nebojsa Milovanovic and Steve KenchingtonPowertrain Research Department, Lotus Engineering, UK

10/03/20062

Overview of Presentation

• Advanced diesel combustion: basics, challenges and potential solutions

• What is Lotus AVTTM system

• Reasons for using Lotus AVTTM system

• AVTTM system application for diesel engines’ results

– Advanced combustion

– Pneumatic hybridisation (Air-hybrid)

– Advanced turbocharging

• Summary

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Why Advanced Diesel Combustion?

0

0.005

0.01

0 0.1 0.2NOx

PM

HCCI

US 2010

How to meet US2010 emissionsand improve engine efficiency?

• Proposed NOx levels are unlikely with current state-of-the-art diesel combustion and considerable SFC penalties are incurred

• After-treatment regeneration further increases SFC penalties

US 2010 (Tier 2 Bin 5) emissions level:• NOx < 0.2 g/hp-hr• PM < 0.01 g/hp-hr(CO < 15.5 g/hp-hr and HC < 0.14 g/hp-hr)

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Challenges:

• Enlarging HCCI operational area towards higher loads, i.e. reducing a high rate of heat release

• Reducing excessive CO and HC emission at low loads• Obtaining smooth transition in ‘mixed mode’ CI-HCCI engines • Increasing efficiency (and pressure ratio / air flow) of charging

system• Keeping existing engine geometry unchanged

Solutions:

• Managing the coolant temperature• Change the ratio between piston and turbine work

• Using a Lotus Fully Flexible Valve Train - AVTTM

Advanced Combustion - Challenges & Solutions

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What is Lotus AVTTM

Lotus Active Valve Train - AVTTM:– Electro-hydraulic valve system with full

flexible control over valve timing, lift and velocity.

– Capability to run different valve profiles (trapezoidal or triangular) and to open / close valves more than once per engine cycles.

Crankshaft Angle

Val

ve li

ft

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HDD Engine With AVTTM on a Test Bed

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Reasons for Using AVTTM for Advanced Diesel Combustion

Potential benefits:

• Could achieve US 2010 emission standards without

aftertreatment equipment and increase engine

efficiency without fuel economy penalty

• Has potential to improve fuel economy by 5%

• Enables pneumatic hybridisation

• Has potential to increase efficiency of pressure

charging system

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AVTTM - Emissions Reduction & Fuel Economy Improvement

Targets:

• Significant reduction in HC and NOx emissions without using after-treatment equipment

• Fuel consumption reduction• Increase in thermodynamic efficiency (i.e. engine power / torque)• Keeping existing engine geometry unchanged

Approach:

• Multistage combustion process

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Multistage Combustion ResultsResults obtained on gasoline operations:

• Emission reduction (engine out emissions):-NOx < US 2010 emissions-THC < 100 ppm

• Torque increase: - from 50% to 100%

• SFC:-from 10% to 15%

Applicable to IDI and DI diesel engine

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AVTTM Enables - Pneumatic Hybridization

Targets:

• Reducing engine braking losses by recovering braking energy • Store that energy and later transform into positive work, e.g.

use it to drive engine from the standstill

Approach:

• A pneumatic hybrid which pumps air to a receiver during vehicle braking and uses the engine as an air motor to launch the vehicle from standstill

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• A two-litre 4-cylinder engine charges a 30 litre reservoir to 22 bar in 12 secs with the engine driven at 5000 rev / min (85% achieved in 6 secs)

• Available motor torque drops rapidly - from 35 to 0 Nm in 8 secs (two-stroke @ 1000 rev/min)

Pneumatic Hybridization Results

10/03/200612

AVTTM Enables - Advanced Turbocharging

a b a b a b a bI/C

I/CCat.

Bypass

Valve Timing ProvidesSystem Control (Wastegate)Function

All gases passthrough 2nd Turbine:No Wastegate

AirFilter

2-Stage series system

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Advanced Turbocharging / Divided Exhaust Period

a b a b a b a bI/C

Cat.Air

Filter Exhaust blow-down line / valve

Exhaust scavenging line / valve

TDC over.

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Advanced Turbocharging / Divided Exhaust Period

a b a b a b a bI/C

Cat.

Benefits:• Cold start catalyst light-off time reduced• Full load performance enhancement• Pumping losses reduced• Pulse interaction avoided• Fully optimised angle area

AirFilter

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AVTTM for Advanced Diesel Combustion - Economic Benefits

Diesel engine for US 2010 emissions with Lotus AVTTM

• Deleted• Deleted• Deleted• Less costly 2-series

turbo-charging system• Deleted• Deleted• Oxy cat

Conventional diesel engine for US 2010 emissions

• Valve train• Camshaft• ‘Jake brake’• Costly premium 2-series

turbo-charging system• DPF system• SCR system• Oxy cat

Vs.

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AVTTM for Advanced Diesel Combustion - Economic Benefits

Diesel engine for US 2010 emissions with Lotus AVTTM

• Deleted• Deleted• Deleted• Less costly 2-series

turbo-charging system• Deleted• Deleted• Oxy cat

Conventional diesel engine for US 2010 emissions

• Valve train• Camshaft• ‘Jake brake’• Costly premium 2-series

turbo-charging system• DPF system• SCR system• Oxy cat

Vs.

Potential to Improve Performanceand

Save Money

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Summary

1. Lotus AVTTM could achieve 2010 emission standards without

aftertreatment equipment and increase engine efficiency without

fuel economy penalty

2. Has potential to improve fuel economy by 5 %

3. Enables pneumatic hybridisation

4. Has potential to increase efficiency of pressure charging system

Potential to Reduce Costs Compared

to Current 2010 Solutions

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