Non-Intrusive In-Cylinder Pressure Measurement of Internal Combustion Engines 1999-01-0544

The monitoring of in-cylinder pressure on internal combustion engines is a costly and intrusive process. Current methods include high cost, miniature pressure transducers mounted in the cylinder head. The transducers have direct access to cylinder pressure, and give a high degree of accuracy. The disadvantage of using this intrusive method is the cost of the sensors and modification of the cylinder head. The monitoring of in-cylinder pressure is usually restricted to research engines or large marine diesels. However, the information carried in the pressure trace is significant and is of benefit in condition monitoring and control.The aim of this research is to produce low cost, non-intrusive sensors to enable the monitoring of in-cylinder pressure, on internal combustion engines. This would enable the use of pressure information to be extended into small in-service internal combustion engines.Preliminary results are very encouraging and show a high correlation between the non-intrusive sensors, and the in-cylinder pressure transducers.This paper details the development of the sensors, instrumentation, algorithms and shows the preliminary results.The conclusions drawn in this paper are that a system for the measurement of in-cylinder pressure using low cost non-intrusive sensors is achievable. The results from this work has shown that the integration of real-time pressure information into the control system is now possible using low cost components.