Browse Publications Technical Papers 2000-01-0893
2000-03-06

High DI Fuel Detection via Exhaust Gas Temperature Measurement for ULEV 2000-01-0893

New exhaust emission laws require significant reduction of tailpipe hydocarbon emissions. The cold start phase of engine operation is a critical period when HC emissions must be minimized. High driveability index (DI) or low volatility fuel causes the open loop air/fuel (A/F) ratio during an initial cold start of the engine to shift lean which in turn contributes to unstable combustion. To compensate for this lean shift, the open loop A/F ratio must be commanded richer than necessary to allow acceptable driveability with high DI fuels which consequently increases tailpipe HC emissions. With engine cold start conditions being equal, (coolant temperature, engine speed, engine load, ignition timing, and commanded A/F ratio), the difference in cold start engine-out A/F ratio can only be attributed to the volatility characteristics of the fuel. The A/F ratio in a combustion chamber and hence, the temperature of the exhaust gas, is a function of the volatility of the fuel.
The recent development of fast response, wide range platinum RTD type sensors for exhaust gas temperature measurement makes possible a method for indirectly measuring differences in A/F ratio during the initial cold start phase of engine operation.
This paper reports the results of an evaluation comparing the engine out exhaust gas temperatures during cold starts to actual engine out A/F ratios using low and high DI fuels and shows a method which may be used to detect the cold start volatility characteristic of the fuel.

SAE MOBILUS

Subscribers can view annotate, and download all of SAE's content. Learn More »

Access SAE MOBILUS »

Members save up to 16% off list price.
Login to see discount.
Special Offer: Download multiple Technical Papers each year? TechSelect is a cost-effective subscription option to select and download 12-100 full-text Technical Papers per year. Find more information here.
We also recommend:
TECHNICAL PAPER

High Temperature Measurements for On-Board Diagnostics of LEV/ULEV Systems

942054

View Details

TECHNICAL PAPER

Closed Loop Catalyst Temperature Feedback for Controlled Catalyst Lightoff and Diagnostics for ULEV

1999-01-0311

View Details

TECHNICAL PAPER

Development of High Performance Catalyst Temperature Sensor for NOx Catalyst Control

1999-01-0615

View Details

X