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The cylinder head gasket with integrated combustion pressure sensors (CHGICPS) reported here targets advanced engine controls and in particular those based on the HCCI, PCCI, or LTC combustion principles, for gasoline, diesel, and alternative fuel engines. Due to the fiber optic combustion pressure sensor's (CPS) accuracy at low pressure during compression integrated into the CHGICPS, this device aims at in-cylinder prediction of mass air flow as well as in-cycle closed loop control of pilot fuel injection in a diesel engine. This paper reports on a replaceable CPS which allows installation and removal from the cylinder head gasket (CHG) without the need for removing the engine head. At the same time the distance layer thickness of CHGICPS is minimized to 2.5 mm and 3.4 mm, depending on the access ability and space constraints around coolant and lubrication ports in the engine.

A fiber optic in-cylinder combustion pressure sensor system design is presented that exhibits the necessary operation and cost characteristics required for combustion pressure-based engine control applications. The sensor system consists of a small, spark plug-integrated, rugged, and high temperature operable sensor head; a low cost optoelectronic transceiver including LEDs, photodiodes, and simple optical couplers; and a DSP-based signal processing circuitry intended for future ASIC integration. A theoretical approach is developed to predict sensor response and signal-to-noise performance. The agreement between theoretical analysis and experimental results demonstrates that the present low cost system design results in required signal-to-noise performance and provides pressure measurement accuracies better than 5%.