Effects of various intake valve timings and spark timings on combustion, cyclic THC and NOX emissions during cold start phase with idle operation in CVVT engine

Kwanhee Choi, Hyungmin Lee, In Goo Hwang, Cha Lee Myung, Simsoo Park

Research output: Contribution to journalArticle

14 Citations (Scopus)

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 languageEnglish
Pages (from-to)2254-2262
Number of pages9
JournalJournal of Mechanical Science and Technology
Volume22
Issue number11
DOIs
Publication statusPublished - 2008 Nov

Keywords

  • CVVT
  • Cold transient start
  • Fast response gas analyzer
  • Spark retardation
  • Valve overlap

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering

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