Study of Low-Speed Pre-Ignition in Boosted Spark Ignition Engine

• Published in: SAE International journal of engines Vol. 7; no. 2; pp. 584 - 594
• Main Authors: Okada, Yoshihiro, Miyashita, Shigeki, Izumi, Yoshihiro, Hayakawa, Yutaka
• Format: Journal Article
• Language: English
• Published: Warrendale SAE International 01.07.2014; SAE International, a Pennsylvania Not-for Profit
• Subjects: Combustion; Combustion chambers; Composite particles; Cylinders; Engines; Gasoline engines; Ignition; Ignition temperature; Low speed; Observational research; Spark ignition; Wetting
• ISSN: 1946-3936; 1946-3944; 1946-3944
• DOI: 10.4271/2014-01-1218

This paper analyzes low-speed pre-ignition (LSPI), a sudden pre-ignition phenomenon that occurs in downsized boosted gasoline engines in low engine speed high-load operation regions. This research visualized the in-cylinder state before the start of LSPI combustion and observed the behavior of particles, which are thought to be the ignition source. The research also analyzed pre-ignition by injecting deposit flakes and other combustible particulate substances into the combustion chamber. The analysis found that these particles require at least two combustion cycles to reach a glowing state that forms an ignition source. As a result, deposits peeling from combustion chamber walls were identified as a new mechanism causing pre-ignition. Additionally, results also suggested that the well-known phenomenon in which the LSPI frequency rises in accordance with greater oil dilution may also be explained by an increase in deposit generation.