Air/fuel ratio control method for a lean burn combustion engine

摘要

A technique is disclosed for operating an internal combustion engine (50) near the lean burn limit. This technique includes sensing a first characteristic corresponding to a mean effective pressure (MEP) of the engine (50) and a second characteristic corresponding to fluid pressure (IMP) in the intake manifold (56). An engine performance criterion is established as a function of the first and second characteristics (MEP and IMP). This performance criterion corresponds to an observed emission rate of a pollutant from the engine (50). A target for the performance criterion is selected which corresponds to lean burn operation of the engine (50) with a limited emission rate of a pollutant. A mixture of air and fuel provided for combustion by the engine (50) is controlled in accordance with the performance criterion and the target. The performance criterion may correspond to: ((BMEP x IMT)/IMP). Furthermore, this technique may be applied to lean burning, gaseous-fuelled engines configured to drive an electrical power generator.