Spark Plug Integrated Fiber Optic Sensor System for Internal Combustion Engine Monitoring and Control

This research addresses critical needs in the areas of electronic control and monitoring of internal combustion engines that require low-cost, durable, accurate, high-temperature viable, and small-size fiber optic pressure sensors for real-time in-cylinder combustion pressure measurement. By employing a novel tapered optical fiber-based sensor design to significantly improve signal modulation levels and by using triple-wavelength0based measurement of optical thin-film interference coating spectral modulations for integrated temperature sensing, we seek to demonstrate a spark plug-integrated and temperature-compensated combustion pressure sensor system that exhibits accuracies better than 2% and operating temperatures up to 550oC. This research addresses high-temperature durability requirements by combining a reliable metal-diaphragm-based design with a hermetically sealed sensor construction. We week to significantly reduce costs of optoelectronic transceivers by developing a low-cost, tapered optical fiber bundle-based coupler design. This approach enables use of low-cost light sources, and alleviates critical alignment requirements. These critical issues have previously hampered fiber optic sensor applications in automotive industry. The multi-wavelength approach compensates for errors induced by factors encountered in an engine setting, such as vibrations, accelerations, and wide ambient temperatures. In Phase I of this research, feasibility of such sensor systems will be demonstrated. Anticipated Benefits: This project will culminate in the development of a low-cost, spark-plug integrated, accurate, durable, error- and temperature-compensated combustion pressure sensor system for internal combustion engine monitoring and closed-loop control applications. The close-loop engine controls based on the in-cylinder pressure information can lead to improved efficiency for fuel saving and pollution reduction, improved reliability, and enormous economical benefits.