Methods and apparatus for combustion sensing and engine management

摘要

In order to sense the onset of combustion e.g. in a diesel type engine, a probe 2 to which an alternating voltage is applied is provided in a combustion space 1 within a cylinder head. At an appropriate point fuel 8 is injected into the combustion space and combusts. At this point the dielectric properties of the fuel/air mixture change because the fuel/air mixture breaks up to form a plasma of ions and radicals. This causes a change in the capacitance of the probe and hence causes the current flowing therein to undergo a change in phase. This change in phase is detected 9, 10, 11 and provides an accurate indication of the start of combustion within the cylinder. Further monitoring of the probe capacitance can provide information concerning the further progress of combustion, the composition of the combustion products, likely emissions and so forth which may be used to control the fuel supply to the engine.