KNOCKING DETECTION OF A GASOLINE-ENGINE BY UTILIZING AN OPTICAL-FIBERWITH SPECIFIC REFRACTIVE-INDEX COMPOSITION

Abnormal combustion of a gasoline engine is often accompanied by a sha rp metallic noise called knocking. A recently proposed method of in-cy linder pressure measurement is applied to detect the knocking, where t he bending power loss of a single-mode fiber with specific refractive- index composition is utilized, The high-frequency response of a protot ype sensor is obtained with a small structure to utilize the bending m echanism that is installed into an engine head gasket. Knocking signal s are detected in a wide range of trace-to heavy-knock conditions. (C) 1998 Optical Society of America.