Detection Frequency Optimization and Experimental Validation for Enhanced Knock Detection Accuracy

Tomoya Niki･Tomokazu Onda･Ryo Adachi･Shouki Nakaya･Hironao Satou･Masayasu Nagado･Kouki Kishimoto･Hiroya Takai (SUBARU)

In the development of high-efficiency engines aimed at achieving carbon neutrality (CN), maximizing hardware performance is necessary; however, this increases the risk of abnormal combustion events such as knocking, and makes it more difficult to distinguish abnormal combustion from normal combustion.To achieve both reliability and performance, technologies capable of accurately detecting abnormal combustion are essential.This report presents detection frequency optimization and experimental validation for enhanced knock detection accuracy.

Effect of alicyclic hydrocarbons on knocking intensity

Yamato Maruyama･Michio Nakano (Nippon Institute of Technology)･Kuniyoshi Eto (YAMABIKO)

In a two-stroke gasoline engine, knocking intensity became higher by using fuels which contain cyclohexane. In this study, the relationship between molecular structure and knocking intensity was experimentally investigated. As a result, it was suggested that the existence of a methyl group and a double bond in molecules affects knocking intensity.

Effect of Cycle-to-Cycle Variation of Combustion on Knocking

Taisei Shimizu･Shota Okuyama･yu Otoshi･yuki Imagawa･Kazunari Kuwahara (Osaka Institute of Technology)

LW integral shows that at the autoignition timing of 15 degrees ATDC, ignition delay time is about 10 crank-angle degrees essentially, regardless of engine rotating speed. When a fast cycle increases in-cylinder pressure and temperature so that ignition delay time can shorten to 10 degrees, autoignition occurs essentially. An SI engine has been operated using several fuels with different RON's, and knocking has been set at different timings. The experimental data have suggested that knocking is controlled by fast cycles in the cycle-to-cycle variation of combustion.

Knock Suppression and Thermal Efficiency Improvement in a Gasoline Engine Using Fuel Reforming

Shota Tsuji (Hokkaido university, Graduate School of Engineering)･Gen Shibata･Hideyuki Ogawa (Hokkaido university, Research Faculty of Engineering)･Jun Gotou (Yamaha Motor)

Hydrogen and methane addition to spark-ignition engines has been shown to suppress knock, and this effect is further enhanced under boosted conditions. In this study, the knock suppression effect of hydrogen and methane was quantitatively evaluated through engine experiments and examined using a detailed chemical reaction model. Furthermore, the combined effect of fuel reforming and boosting was investigated. The influence of reformed gas, generated at various exhaust gas temperatures, on thermal efficiency was analyzed. Based on these results, the effectiveness of fuel reforming and the optimal operating conditions for maximizing engine efficiency were discussed.