An electromagnetic actuator for a control valve module in an engine fuel injector, the module being a replaceable, independent element of the injector. The actuator has a stator with electromagnetic coil windings on a bobbin located within the control valve module. An armature is connected to a control valve in the module. The bobbin supports and precisely positions connector pins for the coil windings for registry with an external electrical wire harness.

A unitary fuel injector and nozzle assembly comprising a high-pressure piston pump and a cylinder body that define a high-pressure fuel pump chamber. An injector nozzle assembly is in fluid communication with the pump chamber and is held in place by a nozzle nut detachably secured to the cylinder body. A nozzle valve assembly includes a spring located in a spring cage within the nozzle nut. A control module is assembled between the cylinder body and the spring cage, the module including a module body having a valve chamber that receives a control valve and a stator assembly as separate and removable elements of the module whereby the stator assembly, the nozzle valve assembly and the control valve can be changed independently of the other elements of the injector to meet various operating requirements.

A valve is formed to resist snap-action closure forces and provides a smooth closing action to minimize or eliminate water hammer. The valve is opened and closed by modulating the relative air pressures above and below a piston in the valve. Because the air pressures above and below the piston produce partially offsetting forces on the piston, the net closure force on the valve plunger is limited, and the rate of valve closure is reduced enough to achieve the effect of minimizing water hammer. A separate vent port volume may vent to atmosphere to further limit valve closure speed, and to further reduce water hammer. The valve can provide the capability to control the flow of fluids over a wide temperature range over a long service life while reducing or eliminating water hammer. The valve is well suited for use in injection mold temperature control systems.

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.

A fuel injector assembly comprising an engine camshaft driven piston plunger in a plunger body, a control valve, an electromagnetic actuator for stroking the control valve between limiting positions and a valve stop assembly establishing a first limiting valve stroke position when the control valve is fully open and a second valve stroke position corresponding to a reduced fuel delivery pressure prior to a main fuel pressure pulse in a fuel injection event.