Development of PN Reduction Technology for Catalyst Warm-up in a DI Gasoline Engine

ガソリン直噴エンジンにおける 触媒早期暖機モード運転時の排出微粒子数低減技術の開発

Gasoline direct injection (DI) has been widely applied to high-compression-ratio engines for better thermal efficiency. The reduction of particulate number (PN) emissions is the major concern of a gasoline DI engine due to the introduction of PN standards in Euro 6 emission regulations. PN emissions during the catalyst-warm-up operation are substantially high. Therefore, it is important to focus on combustion characteristics during this operation. This paper describes an investigation to understand the mechanisms of particulate formation using optical engine measurements and CFD simulations. As a result, the soot formation caused by pool fire on the piston surface was considered to be a main source of PN emissions. Then, to evaluate the amount of soot quantitatively, the two-color method was conducted and the amount of soot was quantified by KL factor. It was found that PN emissions were strongly correlated with KL factor. To reduct PN emissions, the injection strategy was optimized. 70% decreasing of KL factor is achieved at the optical engine during the catalyst-warm-up operation and the vehicle PN emissions during the NEDC is reduced by 66%.近年,欧州における粒子状物質の個数(PN)の規制に伴い,ガソリン直噴エンジンの重要課題として,PN 低減に向けた技術開発が盛んに行われている.そのPN の多くは,始動直後の触媒早期暖機運転時に排出される.本稿では,上記運転時のPN 生成の現象解明と要因分析を,可視化エンジンを用いて進め,その低減技術を開発した.

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  • English
  • Japanese

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  • Accession Number: 01673385
  • Record Type: Publication
  • Source Agency: Japan Science and Technology Agency (JST)
  • Files: TRIS, JSTAGE
  • Created Date: May 15 2018 3:03PM