Abnormal combustion of a gasoline engine is often accompanied by a sharp metallic noise called knocking. A recently proposed method of in-cylinder pressure measurement is applied to detect the knocking, where the bending power loss of a single-mode fiber with specific refractive-index composition is utilized. The high-frequency response of a prototype sensor is obtained with a small structure to utilize the bending mechanism that is installed into an engine head gasket. Knocking signals are detected in a wide range of trace- to heavy-knock conditions.
© 1998 Optical Society of America
Original Manuscript: July 15, 1997
Revised Manuscript: October 13, 1997
Published: March 1, 1998
M. Komachiya, H. Sonobe, T. Fumino, T. Sakaguchi, K. Kawakami, S. Watanabe, and T. Sasayama, "Knocking detection of a gasoline engine by utilizing an optical fiber with specific refractive-index composition," Appl. Opt. 37, 1152-1158 (1998)