Fuel injector with directly controlled dual concentric check and engine using same

A method of injecting fuel, comprising the steps of:

• providing a fuel injector with a plurality of nozzle outlets, and a directly controlled dual concentric check assembly that includes a closing hydraulic surface exposed to fluid pressure in a check control chamber;
• connecting said check control chamber to a low pressure passage;
• moving said dual concentric check assembly to one of a first configuration and a second configuration in which first and second portions of said nozzle outlets are open to a nozzle chamber, respectively;
• connecting said check control chamber to a high pressure passage;
• and
• biasing said dual concentric check toward a closed configuration in which said plurality of nozzle outlets are blocked at least in part via a first spring and a second spring.

An engine comprising:

• a plurality of directly controlled dual concentric check fuel injectors attached to an engine housing;
• each of said fuel injectors a dual concentric check assembly at least partially positioned in an injector body and including a closing hydraulic surface exposed to fluid pressure in a check control chamber;
• said dual concentric check assembly being movable between a first configuration in which a plurality of nozzle outlets are blocked to a nozzle chamber, a second configuration in which a first portion of said nozzle outlets are open to said nozzle chamber, and a third configuration in which all of said nozzle outlets are open to said nozzle chamber;
• and
• a source of liquid fuel fluidly connected to each of said fuel injectors, and said source of liquid fuel including at least one of a unit pump and a common rail.