This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Optimization of Cam Phase and Spark Retard to Improve Catalyst Warm- Up in the Cold Start Period of An SI Engine
Technical Paper
2004-05-0377
Sector:
Language:
English
Abstract
The effects of spark timing and exhaust valve timing change on exhaust gas temperature during cold start period of an SI engine are studied through engine bench tests. Optimal spark timing and exhaust valve timing are investigated to find the best conditions for rapid warm up of catalysts. The exhaust gas temperature increases when the spark timing or valve timing are retarded individually, due to late combustion or slow flame speed. Therefore, exhaust gas temperature shows a large increase when the two timings are retarded simultaneously, with the cost of COVimep. Combustion stability during cold start deteriorated under these retarded conditions. To increase exhaust gas temperature for fast warm up of catalysts while maintaining combustion stability, an optimal condition for spark and valve timing retard should be applied for the cold start period.