Development of Combustion Technology for Improving Scavenging Process and for Reducing Catalyst Warm-Up Time in a High-Compression-Ratio Gasoline Engine

Abstract

The high compression ratio is effective in improving the thermal efficiency for a spark-ignition gasoline engine. However, the exhaust emissions are deteriorated by the increased catalyst warm-up time, which results from (1) the reduced exhaust gas temperature caused by the elevated expansion ratio and (2) the elongated exhaust pipe for better scavenging efficiency. To meet the stringent emission regulations, the technology development was conducted for retarding the combustion phasing and for improving the scavenging process in a high-compression-ratio engine. The results show that both high environmental performance and high engine torque are achieved.