An approach to multiplex in-cylinder pressure measurement that utilizes a single-mode optical fiber with specific refractive-index composition has been proposed. The sensing fiber has been designed to show a certain amount of optical power loss with a small change in the fiber-local-bend radius. Along with pressure-transferring diaphragms the sensing fiber was embedded into the head gasket of a four-cylinder gasoline engine. The internal-pressure change in each combustion chamber was detected on the basis of bending power loss in the fiber. Combustion pressure peaks for each cylinder were clearly observed.
© 1996 Optical Society of America
M. Komachiya, H. Sonobe, S. Oho, M. Kurita, T. Nakazawa, and T. Sasayama, "Multiplex in-cylinder pressure measurement utilizing an optical fiber with specific refractive-index composition," Appl. Opt. 35, 1143-1150 (1996)