Patent ID: 7302918

Claim:
A method of operating a gaseous-fuelled direct injection internal combustion engine defining a combustion chamber, said method comprising: (a) determining an engine speed and engine load for said engine for a cycle of said engine; (b) during said cycle of said engine: (i) directing an intake charge into said combustion chamber, said intake charge having an exhaust gas recirculation (EGR) concentration, (ii) compressing said intake charge within said combustion chamber during a compression stroke of said engine, (iii) directly injecting a gaseous fuel into said combustion chamber at a main fuel timing, (iv) directly injecting a quantity of a pilot fuel into said combustion chamber at a pilot fuel timing relative to said main fuel timing selected by reference to an indicator of said EGR concentration, said engine speed and said engine load, said pilot fuel capable of auto-igniting at a first injection crank angle when a piston is near or at top dead center within said combustion chamber, said combustion chamber partially defined by said piston, (v) burning said gaseous fuel and said pilot fuel, said gaseous fuel ignited as a result of combustion of said pilot fuel.