An evaluation of an optically-based, cylinder pressure sensor in a single-cylinder, research, diesel engine

Abstract

Engineers have long searched for a viable method to reliably measure cylinder pressure in real-world, internal combustion engines during normal operation. Although many devices to measure cylinder pressure in a laboratory situation exist, none exist that would serve outside the lab. However, a new optical strain gauge based on the fiber Fabry-Perot interferometer (FFPI) may prove to be effective in realworld situations. One FFPI sensor embedded in a fuel injector bolt and three FFPI sensors embedded in head bolts were tested under a variety of operating conditions on a single cylinder, research, diesel engine. The sensors' pressure vs. crank angle output was compared with the output of a piezoelectric pressure transducer mounted, in the engine head. Plots of the FFPI output indicate that the sensor has promise if several sources of noise and tracking error can be eliminated.