Abstract: A fuel injector assembly for an emissions-based EMD 710 locomotive dieselengine. The fuel injector assembly includes a needle slidably positioned within a bore of a valve body of the injector assembly, where fuel pressure introduced into a bore chamber causes the needle to open a spray tip. A spring mounted within the bore forces the needle to close the spray tip when the fuel is not being applied. The spring is a dead coil spring including inactive coils where at least portions of the coils at both ends of the spring are in intimate contact with each other so as to reduce spring wear during operation of the assembly. Because the dead coil spring has reduced wear, the VOP set point of the fuel injector assembly can be reduced, which reduces NOx emissions.

Abstract: A nozzle assembly for a fuel injector having a needle valve for controlling an injector valve orifice, the needle valve being subjected to a spring force and a fluid pressure force. The needle valve registers with a fuel delivery orifice and is movable into and out of engagement with a valve seat surrounding the orifice. The needle valve is normally biased to a valve closing position by a spring located in a spring cage. The spring cage becomes pressurized upon movement of the needle valve toward the needle valve open position, whereby a positive pressure is maintained in the spring chamber throughout the fuel injection event. A calibrated bleed orifice allows the spring chamber pressure to decay to a low value between injection events.

Abstract: A nozzle assembly for a fuel injector having a needle valve for controlling an injector valve orifice, the needle valve being subjected to a spring force and a fluid pressure force. The needle valve registers with a fuel delivery orifice and is movable into and out of engagement with a valve seat surrounding the orifice. The needle valve is normally biased to a valve closing position by a spring located in a spring cage. The spring cage becomes pressurized upon movement of the needle valve toward the needle valve open position, whereby a positive pressure is maintained in the spring chamber throughout the fuel injection event. A calibrated bleed orifice allows the spring chamber pressure to decay to a low value between injection events.

Abstract: An apparatus and method for varying the current levels of a fuel injection signal used in connection with an electronically controlled hydraulic actuator unit injector fuel system is disclosed. The apparatus and method varies the current level of the fuel injection signal delivered to the unit injector based on sensed engine parameters, which preferably include a sensed pressure of hydraulic actuating fluid and a sensed temperature of the engine.

Abstract: An apparatus and method for varying the duration of current levels of a fuel injection signal used in connection with an electronically controlled hydraulic actuator unit injector fuel system is disclosed. The apparatus and method varies the duration of the pull-in current of the fuel injection signal delivered to the unit injector based on sensed engine parameters, which preferably include a sensed temperature of the engine and engine speed.