Evaluation of a Spark-Plug-Integrated Fiber-Optic Combustion Pressure Sensor

We present design considerations of a diaphragm-type spark-plug-integrated fiber-optic combustion pressure sensor employing low-cost sensor and optoelectronic components suitable for large-scale production. Sensor system evaluation data are presented for high-engine-load and high-combustion-temperature conditions, and for knock detection. The fiber-optic sensor output closely resembles that of a heat-sunk, flame-shielded instrumentation-grade piezoelectric reference transducer, and demonstrates a high degree of temperature stability. Better than 4% accuracy is demonstrated over a full-scale pressure range.