Non-Intrusive Low Cost Cylinder Pressure Transducer for Internal Combustion Engine Monitoring and Control

The objective of this research is to develop a concept for a low cost, non-intrusive sensor to enable the monitoring of in-cylinder pressure on internal combustion engines. This research should enable the use of cylinder pressure information to be extended into smaller in-service internal combustion engines particularly when “closed loop” control is required to control combustion.

This paper details the development results of a new concept for a low cost non-intrusive cylinder pressure sensor utilizing the movement of an engine valve when subjected to cylinder pressure. The conclusions drawn in this paper are that a system for measuring in-cylinder pressure using a valve movement sensor is possible at the required accuracy and could be lower cost than the current best technology. In addition the long term durability of this concept should be better because it uses a robust engine valve for the diaphragm element and locates the sensor in an area of the engine where it will experience minimal effects from the cyclic engine operating conditions.

Preliminary results are very encouraging and show a potential for high correlation between the concept non-intrusive sensor and a reference in-cylinder pressure transducer. The results show that this concept could detect start of combustion in LTC and HCCI engines after additional development. This new technology could be fitted to most existing engines with only minor changes to the engine design and could also be used for valve actuation detection and control. This work shows that a robust low cost cylinder pressure measurement system is possible for the integration of real-time pressure information into a wider range of production engine control systems.