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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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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
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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