異なる圧縮比におけるEGRがHCCI燃焼に与える影響

概要

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The HCCI engine has attracted for high efficiency and low exhaust emissions. However, the HCCI combustion process has two issues to be resolved : ignition timing control, slower combustion. In order to overcome these issues, it is necessary to investigate in detail the low-temperature oxidation reactions that distinctly characterize HCCI combustion and the state of combustion. In this study, spectroscopic measurements were made at a high compression ratio of approximately 15:1, which is sufficiently high for practical operation. Simultaneously, the combustion condition in the cylinder was visualized via a sapphire observation window that was provided in the top of the cylinder head by taking advantage of the simple structure of the two-stroke test engine. The results revealed that the ignition delay period and the manner in which autoignition occurred tended to differ at different compression ratios when EGR was applied, which is believed to be effective in moderating HCCI combustion.