A multi sensors head gasket to detect and locate knock / Last improvements

Knock prevents to explore potentially interesting areas of engine parameters to improve its efficiency. An instrumented head gasket and an associated methodology have been developed to detect and locate knock inside the combustion chamber in order to provide a relevant tool for engine designer and tuner. The principle is based upon the observation that knock creates first a localized pulse, then a sound wave that is propagated in all directions of the combustion chamber like in a free field, before the first reflections on the chamber walls occur. For each engine cycle, one detects and processes the time at which the sound wave reaches all pressure sensors on the gasket. The instrumented gasket replaces the engine head gasket by securing tightness and by allowing non-intrusive measurements: 8 piezoelectric sensors, regularly distributed in the chamber, are inserted in the gasket. To this day, 3 head gaskets have been used for intensive test series on one-cylinder engines. The full system includes the instrumented gasket, conditioners, the acquisition system and the post-processing software.