A FUEL INJECTION SYSTEM AND METHOD OF OPERATION FOR A GASEOUS FUELLED ENGINE WITH LIQUID PILOT FUEL IGNITION

摘要

A pilot fuel injection valve is provided that is mountable in a cylinder head of an engine and is operable to inject a liquid pilot fuel directly into a combustion chamber. The pilot fuel injection valve comprises a cooling system to keep the pilot fuel at a temperature that is lower than the lowest initial boiling point for the pilot fuel that occurs inside the fuel injection valve. The pilot fuel injection valve further comprises a thermally insulated nozzle so that it's outer surface is not cooled by the cooler cylinder head and the cooler pilot fuel held inside the fuel injection valve whereby the nozzle's outer surface can be heated to a temperature that is not significantly lower than the final boiling point of the pilot fuel so that a significant amount of pilot fuel does not condense on the nozzle surface during engine operation. When a gaseous fuel injection valve also has a nozzle disposed inside the combustion chamber it too can be thermally insulated to allow it to maintain a surface temperature during engine operation that is not significantly lower than the final boiling point of the pilot fuel. The method cools the pilot fuel inside the pilot fuel injection valve to prevent or reduce the partial vaporization of pilot fuel inside the nozzle orifices and in other parts of the fuel injection valve. The method further comprises thermally insulating the nozzle so that when the engine is running, the surfaces that come into contact with pilot fuel within the combustion chamber maintain a surface temperature that is not significantly lower than the final boiling point of the pilot fuel.