Pre-ignition-prevention control method in spark-ignition engines by detecting precursory cycles with an ion-current sensor

Abstract

In gasoline engines with a higher compression ratio, abnormal combustion, such as pre-ignition and knocking, tends to occur due to higher temperature in the combustion chamber, which leads to lower engine performance. To prevent pre-ignition from occurring, we propose a pre-ignition-prevention control method that involves using an ion-current sensor integrated in an ignition system. The pre-ignition and precursory cycles are detected from the ion-current intensity and spark-discharge duration estimated from ion-current signals. Fuel-injection is increased to cool the mixture in the combustion chamber after the abnormal combustion (precursory) cycle is detected. In a commercial gasoline engine, it was demonstrated that our method can prevent pre-ignition combustion by setting a proper threshold for precursory-cycle detection. The effectiveness of the fuel-injection control was analyzed.

Control Technologies for Advanced Engines and Powertrains: A Review

“…Ion current has been used to obtain flame information and detect misfires (41)(42)(43) , and studies have shown that it can be used to obtain the combustion state even for compression ignition at lean conditions in HCCI (44)(45)(46) engines. In addition, the detection of abnormal combustion, knocking and pre-ignition (47)(48)(49)(50)(51) , and the possibility of detecting precursors to preignition (52,53) have also been reported. Kumano et al (52) investigated the characteristics of ignition precursor phenomena in gasoline engines with a high compression ratio by using an ion current sensor integrated into the spark ignition coil.…”