Patent ID: 8590515

Claim:
A method for powering an Otto-cycle engine using gasoline and compressed natural gas (CNG), the method comprising: (a) determining a quantity of the gasoline and a quantity of the CNG to deliver to a cylinder of the engine during an engine cycle such that combustion within the cylinder occurs at a predetermined air-fuel ratio, wherein determining the quantity of the gasoline and the quantity of the CNG comprises: (i) determining a stock quantity of the gasoline to deliver to the cylinder such that combustion occurs within the cylinder at the predetermined air-fuel ratio when the engine is powered solely using the gasoline; (ii) determining a portion of the stock quantity of the gasoline to substitute with the CNG, wherein the remaining stock quantity of gasoline following substitution is the quantity of the gasoline to deliver to the cylinder; and (iii) determining the quantity of the CNG to deliver to the cylinder from the portion of the stock quantity of gasoline to substitute with the CNG such that combustion of the gasoline and the CNG within the cylinder occurs at the predetermined air-fuel ratio; (b) delivering the quantity of the gasoline into the cylinder via a gasoline injector and delivering the quantity of the CNG into the cylinder via an alternative fuel injector such that the gasoline and the CNG combust during the same combustion event; and (c) combusting the gasoline and the CNG within the cylinder during the same combustion event.