Background:
As automotive spark ignition engine emission standards become increasingly stringent, cold-start emissions performance is receiving added attention. The first sixty to ninety seconds of operation after a cold-start can account for as much as 80% of the hydrocarbon emissions produced during an emissions test. One of the major reasons for this is sluggish catalyst activity at low temperatures. A catalyst must achieve relatively high temperatures, usually above 300°C, before its efficiency rises to a level needed to meet emissions standards.

Cold-Start Hydrocarbon Emission Reduction Study Using Variable Valve Timing Strategies

Abstract:
Variable valve timing systems are generally implemented to increase fuel economy and performance. Control strategies to achieve improved fuel economy and performance have been studied extensively up to this point. However, cold-start strategies that take advantage of variable valve timing technologies are not well understood. The goal of this project is to analyze possible valve timing strategies that will expedite catalyst light-off while reducing the overall hydrocarbon output of the engine prior to light-off. To meet these goals, efficient heat management methods under cold-start conditions will be studied.

Accomplishments: