Method and system for powering an otto cycle engine using gasoline and compressed natural gas

Abstract

Described are methods and systems for powering an Otto-cycle engine using gasoline and compressed natural gas (CNG). The Otto-cycle engine can be powered by 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 pre-determined air-fuel ratio; delivering the quantity of the gasoline to the cylinder via a gasoline injector and delivering the quantity of the CNG to the cylinder via a CNG injector such that the gasoline and the CNG combust during the same combustion event; and combusting the gasoline and the CNG within the cylinder. Delivering CNG and gasoline to the cylinder using separate injectors allows the quantities of CNG and gasoline to vary in response to engine operating conditions, which allows the fuel mixture to be adjusted to satisfy engine power and emissions criteria.