Fuel injection system for diesel engines

Claim 1

An improved system for operating a diesel engine with a combination of diesel fuel and alternative fuel having a low cetane number, wherein the engine includes at least one cylinder having a piston therein to form a combustion chamber at one end of the cylinder, comprising a single fuel injector adapted to be connected with the combustion chamber of said cylinder of the engine, said injector including a cavity therein having a port through which fuel may be injected into the combustion chamber and a valve seat about the port, a valve member shiftable between one position on the seat to close the port and another position spaced from the seat to open the port, means which is responsive to the pressure of fuel in the cavity to urge said valve member to open position, means urging the valve member toward closed postition with a force which is independent of such fuel pressure, means for supplying diesel fuel to the cavity of said injector at a location near the valve seat, means for supplying alternative fuel to the cavity of said injector the diesel fuel being supplied at a relatively low pressure which does not move the valve member to open position, the alternative fuel being supplied at a relatively high pressure which is sufficient to move the valve member to open position at intervals just prior to the movement of the piston of the cylinder of the chamber into which the fuel is to be injected into high center position during its compression stroke, and said fuel supplying means including means to prevent the back flow of fuel therein, and thus maintain the cavity filled with fuel, except when alternative fuel is displaced within the cavity by the supply thereto of diesel fuel, whereby a plume of both fuels having the diesel fuel at its tip is injected into said chamber to enable the diesel fuel to be ignited by the compression in the chamber and the alternative fuel to be ignited by the diesel fuel.