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Emissions and Fuel Economy of Vehicles and Engines in the Real World and On the Road. Leo Breton Mechanical Engineer. Computer-Controlled Vehicles/Engines. All New On-Road Vehicles Growing Non-Road Presence Offer Great Potential to Improve Fuel Economy and Reduce Emissions
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Emissions and Fuel Economy of Vehicles and Engines in the Real World and On the Road Leo Breton Mechanical Engineer
Computer-Controlled Vehicles/Engines • All New On-Road Vehicles • Growing Non-Road Presence • Offer Great Potential to Improve Fuel Economy and Reduce Emissions • But Often Perform Differently in Real World Compared With Laboratory • Certification Process Used for Establishing Performance • Lab Testing Limitations • Engine Calibration Process • Manufacturers Seeking Competitive Advantage
All New Vehicles and Engines Must Meet Numerical Emissions Standards and Must Not Have Defeat Devices • Fuel Economy and Emissions Levels Determined for a Vehicle/Engine Through Manufacturer-Run Certification Testing With Limitations: • Prototype Vehicle/Engine • Calibrated to Test Method • Certification Test Fuel • Professional Driver/Computer • Tightly Controlled Drive Cycle • Laboratory Dynamometer Testing • Simplified Loading Curve • Tightly Controlled Ambient Conditions • Simulated Sensor Inputs for Heavy-Duty
Prohibition of Defeat Devices • “No new gasoline-fueled light-duty vehicle or light-duty truck shall be equipped with a defeatdevice.” • “Defeat Device means an auxiliary emission control device (AECD) that reduces the effectiveness of the emission control system under conditions which may reasonably be expected to be encountered in normal vehicle operation and use, unless:” • Conditions are also substantially included in federal test procedures • Need is justified to protect vehicle against damage or accident • Needed for engine starting
Manufacturer Fueling Calibration • Fueling Matrix a Function of: Lab Limitations • Ambient Temp 68-86 F • Coolant Temp Lab Temp, Cycle, Cooling • Manifold Pressure Lab Altitude, Cycle • Throttle Position Altitude, Cycle • Throttle Rate of Change Professional Driver • Vehicle Speed Cycle • Engine Speed Cycle • Engine Speed Change Cycle, Driver • A/C On/Off
Measuring Emissions and Fuel Economy in Real World • Traditional Equipment Massive / Power Intensive • Auto Industry Considered it Impossible • EPA Didn’t See Fit With Regulatory Framework • Nobody Knew What Was Being Missed • Nobody Thought About It • ROVER Developed to Demonstrate It Was Possible • ROVER Patent is Basis for Commercial Systems
What Has Been Found In Real World? • Emissions Higher Than Expected • Fuel Economy Lower Than Expected For Passenger Cars Even On Same Cycle as Lab • Engines/Vehicles Often Behave Very Differently • Sensitivity to Driver Inputs • “Catalyst Protection”/Reduced FE Under High Loads • Enleanment to Boost Fuel Economy • Calibration Space Not on Appearing on Test • Small Engine “Catalyst Protection” at Normal Highway Speeds • Heavy-Duty Diesel Improved Fuel Economy on the Cheap • Fuel Economy Had Been Higher Than Expected for HDDE With Major Emissions “Hit” • Reduced Standards Were No Guaranty Of Reduced Emissions
ROVER Test of XXXX - NOx at Idle 2000 2 1500 1 O2 (V), Spark Adv./10 NOx NOx (ppm) 1000 0 O2 Sensor Spark Adv. 500 -1 0 -2 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 time (s) ROVER Test of LEV - NOx at Idle 50 4000 40 3000 30 2000 Spark Adv. (deg) RPM Spark Adv. 20 1000 RPM 10 0 0 -1000 -10 -2000 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 time (s) Calibration Not On Test
Small Engine Enrichment Highway Speeds 3.7 g/mi
Calibration Not On Test / Small Engine Protection Fuel Economy Guide: 61/70 Hilly Terrain On-Road 59
HDD Steady-State Fuel Economy Strategy “On the Cheap”
Conclusions and Comments • Laboratory Testing Cycles Are Easily Defeated or Calibrated Around • Laboratory Data Has Not Been a Good Predictor of In-Use Performance • Laboratory Data Makes Bad Models and Leads to Bad Inventories • Regulations Do Not Work Without Effective In-Use Compliance Testing • In-use Fuel Economy is Significantly Lower Than Label Even With Similar Drive Cycle • AECDs (Deliberate Calibration Strategies) Can Be the Dominant Factor in Real-World Performance • Increasingly Sophisticated Fueling Strategies are Likely to Show Up Over Time Will Real-World Fuel Economy Increase Proportionately to CAFE Figures? Are CAFE Figures a Good Basis for Energy Analysis? Don’t We Need a Good Understanding of Real-World Fuel Economy To Become More Energy Independent?