Abstract
In a gasoline SI engine, valve events and spark timings put forth a major influence on overall efficiency, fuel economy, and exhaust emissions. Residual gases controlled by the valve overlap can be used to reduce NOx emissions and the spark retardation technique can be used to improve raw THC emissions and catalyst light-off performance during the cold start phase. This paper investigated the behaviors of the engine and its combustion characteristics with various intake valve timings and spark timings during the fast idle condition and cold start. And cyclic THC and NOx emissions were measured at the exhaust port and their formation mechanisms were examined with fast response gas analyzers. As a result, THCs and NOx were reduced by 35% and 23% with optimizing valve overlap and spark advance during the cold transient start phase. Consequently, the valve events and ignition timings were found to significantly affect combustion phenomena and cold-start emissions.
Original language | English |
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Pages (from-to) | 2254-2262 |
Number of pages | 9 |
Journal | Journal of Mechanical Science and Technology |
Volume | 22 |
Issue number | 11 |
DOIs | |
Publication status | Published - 2008 Nov |
Bibliographical note
Funding Information:This study was funded by BK21 and the Ministry of Commerce, Industry and Energy.
Keywords
- CVVT
- Cold transient start
- Fast response gas analyzer
- Spark retardation
- Valve overlap
ASJC Scopus subject areas
- Mechanics of Materials
- Mechanical Engineering