CO 2 Reduction for Spark-Ignition Engines: Two Paths to Success. John E. Kirwan Delphi Powertrain Systems

Transcription

1 CO 2 Reduction for Spark-Ignition Engines: Two Paths to Success Leveraging Air Delivery and Fuel Injection Technologies to Improve Engine Efficiency John E. Kirwan Delphi Powertrain Systems

2 High Level Gasoline Engine Technology Roadmap PZEV Market Drivers: EURO 5 EURO 5+ Emissions & Fuel Economy CARB CO2 EU 130g/km US Senate CAFE EURO 6 EU 95g/km EU 70g/km US CAFE Update H2 DI-Engine CNG DI-Engine Alternate cycles, VCR, camless HCCI GDi Engine, DICP & VVA & evcp Spray Stratified Boosted GDi Engines Spray Stratified GDi Engines Homogeneous, Boosted GDi Engines, DICP & VVA Homogeneous, Boosted GDi Engines, DICP Homogeneous GDi Hybrid Engines Homogeneous GDi Engines, VVT Alternate Fuel H2 Engine Alternate Fuel CNG, LPG Alternate Fuel Compatible Engine Flex fuel, E10-E100 Boosted PFI Engines Gasoline Hybrid Engine Gasoline Advanced PFI Engine, active VT, mixture motion, PZEV Gasoline PZEV (AIR) Future

3 Where Does the Fuel Energy Go? Fuel Energy Available Combustion Inefficiency Heat Rejection Exhaust Coolant Engine Friction Indicated Work Pumping Losses Shaft Work Accessories Transmission Vehicle Consumption Inertia Aero Drag Rolling Resistance Source: Nat l Acad Eng. (2002) 3

4 Where Does the Fuel Energy Go? Fuel Energy Available Combustion Inefficiency Heat Rejection Exhaust Coolant Source: SAE Engine Friction Indicated Work Pumping Losses Shaft Work Accessories Transmission Vehicle Consumption Inertia Aero Drag Rolling Resistance Source: Nat l Acad Eng. (2002) 4

5 Where Does the Fuel Energy Go? Fuel Energy Available Combustion Inefficiency Heat Rejection Exhaust Coolant Target Domain: Improve Net Engine Efficiency Engine Friction Indicated Work Pumping Losses Shaft Work Accessories Transmission Vehicle Consumption Inertia Aero Drag Rolling Resistance Source: Nat l Acad Eng. (2002) 5

6 Fundamental SI Engine Control Parameters Air htarget: Reduce pumping losses hmethods: qvalvetrain Technologies 8Variable Cam Phasing 8Cylinder Deactivation 8Variable Valve Lift qturbo / Supercharging Fuel Fuel Energy Available Combustion Inefficiency htarget: Reduce heat rejection and pumping losses hmethods: qhomogeneous Gasoline Direct Injection qstratified Gasoline Direct Injection Spark htarget: Proper timing minimizes heat rejection; advanced ignition systems can enable higher dilution combustion strategies Heat Rejection Indicated Work Exhaust Coolant Engine Friction Pumping Losses Accessories Shaft Work Transmission Vehicle Consumption Inertia Aero Drag Rolling Resistance Source: SAE Source: Nat l Acad Eng. (2002) 6

7 Valvetrain Technologies

8 Variable Cam Phasing Functionality: Control air flow through valve timing to gain performance, emissions reduction and fuel economy Application Type Acronym Schematic Ι Benefit Performance Fuel Economy Emissions HC NOx Intake Only IVCP 4-7 % 1-2 % 15% 25% Exhaust Intake TDC Ε Exhaust Only EVCP < 1 % 1-2 % 15% 25% Exhaust Intake TDC Ε Ι Dual Independent (Intake + Exhaust) DICP 5-8 % 1-4 % 30% 40% Exhaust Intake TDC Ε = Ι Dual Equal DECP < 1 % 1-2 % 20% 30% Exhaust Intake TDC 8

9 Variable Cam Phasing Stator Rotor Vane Cam Phaser 9

10 Variable Cam Phasing Benefits 90 Fuel Consum ption - VCP can provide 2 to 3% better BSFC vs EGR Fuel Consumption E xt. EGR C VCP Low Speed Light Load low e r bsfc Increasing EGR % Increasing Overlap Torque 11% Increase 6% Increase N Ox Retard Advance Engine Speed 10

11 Variable Cam Phasing -- evcp Fuel Consumption Functionality Fuel Consum ption helectric - VCP can provide motor 2 3% provides better BSFC ultra vs EGR fast high 90 authority phase shifting independent of 88 engine oil pressure Stator Increasing E xt. EGR 86 Benefits Rotor EGR % C VCP low e r 84 hcam phasing available bsfc immediately during start-up for cold start emissions and 82 Increasing driveability improvement Overlap with stop-start Low Speed 80 vehicles Light Load 78 hincreased phase angle authority and phasing rate enables advanced Vane Cam Phaser N Ox combustion strategies (e.g., HCCI / CAI) 11

12 Cylinder Deactivation Functionality hdisables intake valves from select engine cylinders at lighter engine loads qlost motion between intake cam and valve Benefits h6 8% lower fuel consumption in 6-cyl and 8-cyl engines qdecreased engine throttling for reduced pumping work qdecreased surface area for reduced heat transfer to engine coolant Pumping work reduction Source: SAE

13 Cylinder Deactivation Functionality Deactivation Valve Lifter Hardware Animation hdisables intake valves from select engine cylinders at lighter engine loads Benefits qlost motion between intake cam and valve h6 8% Lower fuel consumption in 6-cyl and 8- cyl engines qdecreased engine throttling for reduced pumping work 13

14 Variable Valve Activation: 2-Step and Continuously Variable (CVVL) Functionality hvaries valve lift, duration and timing (with cam phasing) as a function of engine load to reduce pumping work losses either by discrete 2-step or continuously valve lift profiles (CVVL) henables greater flexibility in engine combustion by de-throttling and increased dilution capability Valve Lift (mm) Valve Lift (mm) E xh a u s t T D C L o w -L ift C a m H ig h -L ift C a m B D C C ra n k P o s itio n (C A D ) GEMS 250a VVA Mechanism Valve Lift Curves 0 Deg -1 Deg -2 Deg -3 Deg -4 Deg -5 Deg -6 Deg -7 Deg -8 Deg -9 Deg -10 Deg 2-Step CVVL Camshaft Rotation (Degrees CW)

15 Variable Valve Activation: 2-Step and Continuously Variable (CVVL) Functionality hvaries valve lift, duration and timing (with cam phasing) as a function of engine load to reduce pumping work losses either by discrete 2-step or continuously valve lift profiles (CVVL) henables greater flexibility in engine combustion by de-throttling and increased dilution capability Benefits h6 8% lower fuel consumption hhelps optimize E85 flex-fuel and HCCI combustion schemes Source: SAE

16 Variable Valve Activation: 2-Step and Continuously Variable (CVVL) 2-Step Example Hardware 2-Step Rocker Arm Tri-Lobe Cam Oil Control Valve Oil Supply Gallery Hydraulic Lash Adjuster Valve Lift (mm) E xh a u s t T D C L o w -L ift C a m H ig h -L ift C a m Higher load 2 Lower load B D C C ra n k P o s itio n (C A D )

17 Variable Valve Activation: 2-Step and Continuously Variable (CVVL) 2-Step Hardware Animation Lower load 17

18 Variable Valve Activation: 2-Step and Continuously Variable (CVVL) CVVL Example Hardware GEMS 250a VVA Mechanism Valve Lift Curves Input cam Rocker/Output cam Valve Lift (mm) Deg -1 Deg -2 Deg -3 Deg -4 Deg -5 Deg -6 Deg -7 Deg -8 Deg -9 Deg -10 Deg Increasing load 2 High lift Low lift Control shaft Camshaft Rotation (Degrees CW) 18

19 Variable Valve Activation: 2-Step and Continuously Variable (CVVL) CVVL Hardware Animation 19

20 Gasoline Direct Injection

21 Gasoline Direct Injection vs. Port Injection Mechanization hinjector tip in combustion chamber hfuel pressure increased from 400 kpa to 20+ MPa hside-mount and central mount injection configurations PFI Injector Intake valve GDi side mount GDi central mount GDi Intake Port Injector Piston Injector Intake Port 21 Piston

22 Gasoline Direct Injection vs. Port Injection Features hin-cylinder evaporation of finely atomized fuel spray qcools intake charge to increase volumetric efficiency and enable knock-free operation at higher cylinder pressures 8Enabler for higher compression ratios, increased boost henables both homogeneous and stratified combustion strategies GDi side mount GDi Intake Port PFI Injector GDi central mount Intake valve Injector Piston Injector Intake Port 22 Piston

23 Gasoline Direct Injection Homogeneous Systems System Features hinwardly-opening, multi-hole GDi Injectors, fuel rail and engine-driven high pressure fuel pump hinjection during the intake stroke focused on complete vaporization and mixing of fuel and air hstoichiometric operation allows emissions control via traditional 3-way exhaust catalyst hreduced in-cylinder temperature enables increased compression ratios (NA) or engine boosting Low Pressure Lines High Pressure Lines Pressure Sensor Fuel Rail 23 High Pressure Pump Injector Wiring Harness and Connectors

24 Gasoline Direct Injection Homogeneous Systems System Features hinwardly-opening, multi-hole GDi Injectors, fuel rail and engine-driven high pressure fuel pump hstoichiometric operation allows emissions control via traditional 3-way exhaust catalyst hreduced in-cylinder temperature enables increased compression ratios (NA) or engine boosting Benefits hfuel economy improvement q1-3% for naturally aspirated q9-12% with downsizing and boost himproved fuel control and rapid catalyst light-off with split-injection during cold start hincreased power and torque Source: Königstein et al (GM): 2008 Vienna Motor Symposium 1.8L engine downsized to 1.4L turbo (with down-speeding) 11% fuel consumption reduction Equivalent performance 24 Source: Schame (Ford): 2008 SAE Congress Presentation

25 Gasoline Direct Injection Homogeneous Systems Key Requirements hoperation at fuel pressures up to 200 bar hinjector packaging for cylinder side mount and central mount hspray generation for good vaporization and mixing without wetting in-cylinder surfaces hgood linear flow range Side mount Central mount Up to 190 mm long Injector Linear Flow Range Comparison Deviation from Linear 20% 15% 10% 5% 0% -5% 0-10% -15% 0 Competition Bosch Ecotec Delphi Delphi Bravo Flow (mg/pulse) 25

26 Gasoline Direct Injection Stratified Systems System Features houtwardly-opening, hollow-cone GDi Injectors, fuel rail and engine-driven high pressure fuel pump hcentral mount injector near spark plug hinjection during the compression stroke for careful placement of fuel mixture in space and time q Multiple injections required to improve confinement of fuel mixture hstratified fuel mixture enables unthrottled operation hreduced in-cylinder temperature enables increased compression ratios (NA) or engine boosting Recirculation Zone 26

27 Gasoline Direct Injection Stratified Systems System Features h Outwardly-opening, hollow-cone GDi Injectors, fuel rail and engine-driven high pressure fuel pump h Stratified mode allows unthrottled operation but requires lean NOx reduction 180 (NOx trap) q Euro vs US Nox emissions Gasoline NA q Low-sulfur fuel h Excellent synergy with turbocharging 140 h Reduces in-cylinder temperatures to enable increased compression ratios (NA) or engine boosting Benefits hfuel economy improvement q10-15% for naturally aspirated q15-20% with downsizing and boost himproved fuel control and rapid catalyst light-off with split-injection during cold start hincreased power and torque NEDC CO2-Emission [g/km] 4 Cylinder Powered Vehicles in Germany Gasoline CNG Diesel Turbo Turbo-diesel Engine Power [kw] 27 MPFI turbo DIG turbo, λ=1,0 Homog. Boosted GDi DIG spray guided, λ>1,0 Stratified GDi European strategy hcurrent barriers to US implementation: qmore stringent NOx standards qlean NOx catalyst durability qfuel sulfur concentration

28 Gasoline Direct Injection Stratified Systems Key Requirements hoperation at fuel pressures up to 200 bar hlow noise in critical frequency range hwell-atomized and well-placed stratified mixture under engine conditions hmultiple injection capability hhigh linear flow range Stable spray under engine conditions 5 bar 10 bar 20 bar Backpressure Fuel Mass (mg/shot) fp = 200 bar 20% 15% 10% 5% 0% -5% -10% -15% Deviation (%) Injector Pulse Width (ms) -20% 28

29 Summary Variable valvetrain technologies and gasoline direct injection offer technology improvements for two critical paths to CO 2 reduction in SI engines hattack pumping losses and heat rejection to improve net engine efficiency hcan be used to optimize alternative fuel performance and advanced combustion strategies (e.g. HCCI / CAI, highly dilute combustion) These innovations will substantially contribute to reducing fuel consumption required by Government and sought by customers happlicable to wide spectrum of engine sizes / power needs hoffer simultaneous performance benefits so that CO 2 reduction need not conflict with fun-to-drive vehicles Fuel Energy Available Combustion Inefficiency Heat Rejection Exhaust Coolant Source: SAE Engine Friction 29 Indicated Work Pumping Losses Shaft Work Accessories Transmission Vehicle Consumption Inertia Aero Drag Rolling Resistance Source: Nat l Acad Eng. (2002)

30 Thank you