Two-stage fuel injection nozzle

A fuel injection nozzle for injecting liquid fuel into a combustion chamber of an internal combustion engine, the nozzle comprising:

• an outer body member having a secondary cavity passing therethrough, one end of said secondary cavity having a reduced diameter cylindrical portion, said secondary cavity transitioning to said cylindrical portion via a conical valve seat;
• an inner body member slidably positioned in said secondary cavity in said outer body member, said inner body member having a pair of axially spaced, circumscribing lands sealingly engaging inner walls of said secondary cavity and defining a circumscribing fuel chamber therebetween, one end of said inner member terminating in a reduced diameter cylindrical extension extending through said cylindrical portion of said secondary cavity, said inner member transitioning to said reduced diameter extension via a conical valve seat adapted for sealingly engaging said valve seat in said outer member, said inner member including a primary cavity passing axially therethrough and exiting adjacent an end of said extension through an aperture, said primary cavity including an internal valve seat at said extension;
• a spring means positioned in said secondary cavity and adapted for urging said inner member in a direction to seat said inner member valve seat against said valve seat in said outer member;
• a valve needle slidably positioned in said primary cavity of said inner member and having a seating surface for sealingly seating against said internal valve seat in said primary cavity;
• a second spring means positioned in said primary cavity and adapted to urge said valve needle into a seating position on said internal valve seat;
• a first fluid passageway extending through said outer body member and terminating in said circumscribing fuel chamber;
• a second fluid passageway extending through said outer body member and terminating at said secondary cavity between said pair of lands and said extension of said inner body member;
• a third fluid passageway extending through said inner body member and connecting said circumscribing fuel chamber to said primary cavity adjacent said seating surface of said valve needle;
• and
• whereby pressurized fluid entering said first fluid passageway fills said circumscribing fuel chamber, flows through said third fluid passageway and reacts against said valve needle to displace said valve needle from its seating position to allow the fluid to be ejected through said aperture in said extension of said inner body member, and further whereby pressurized fluid entering said second fluid passageway reacts against said inner body member to displace said inner body member from said conical valve seat to allow fluid in said second passageway to be ejected from said nozzle.