Investigation into the Relationship between Super-Knock and Misfires in an SI GDI Engine

Jian Gao, Anren Yao, Yeyi Zhang, Guofan Qu, Chunde Yao, Shemin Zhang and Dongsheng Li
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Jian Gao: State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China
Anren Yao: School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
Yeyi Zhang: Technical Center in Dongfeng Motor Co., Ltd., Wuhan 430056, China
Guofan Qu: State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China
Chunde Yao: State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China
Shemin Zhang: Technical Center in Dongfeng Motor Co., Ltd., Wuhan 430056, China
Dongsheng Li: Technical Center in Dongfeng Motor Co., Ltd., Wuhan 430056, China

Energies, 2021, vol. 14, issue 8, 1-18

Abstract: The super-knock poses new challenges for further increasing the power density of spark ignition (SI) engines. The critical factors and mechanism connecting regarding the occurrence of super-knock are still unclear. Misfire is a common phenomenon in SI engines that the mixture in cylinder is not ignited normally, which is often caused by spark plug failure. However, the effect of misfire on engine combustion has not been paid enough attention to, particularly regarding connection to super-knock. The paper presents the results of experimental investigation into the relationship between super-knock and misfires at low speed and full load conditions. In this work, a boosted gasoline direct injection (GDI) engine with an exhaust manifold integrated in the cylinder head was employed. Four piezoelectric pressure transducers were used to acquire the data of a pressure trace in cylinder. The spark plugs of four cylinders were controlled manually, of which the ignition system could be cut off as demanded. In particular, a piezoelectric pressure transducer was installed at the exhaust pipe before the turbocharger to capture the pressure traces in the exhaust pipe. The results illustrated that misfires in one cylinder would cause super-knock in the other cylinders as well as the cylinder of itself. After one cylinder misfired, the unburned mixture would burn in the exhaust pipe to produce oscillating waves. The abnormal pressure fluctuation in the exhaust pipe was strongly correlated with the occurrence of super-knock. The sharper the pressure fluctuation, the greater the intensity of knock in the power cylinder. The cylinder whose exhaust valve overlapped with the exhaust valve of the misfired cylinder was prone to super-knock.

Keywords: gasoline engine; misfire; exhaust pressure; super-knock; pre-ignition (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
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