Patent ID: 8448878

Claim:
A fuel injector comprising: an injector body defining a fuel inlet, at least one nozzle outlet and a drain outlet, and having disposed therein a nozzle chamber, a needle control chamber, and an intermediate chamber; the needle control chamber being fluidly connected to the fuel inlet by a first pathway that includes a Z orifice, and the needle control chamber being fluidly connected to the fuel inlet by a second pathway that includes an F orifice, the intermediate chamber and an A orifice; an electronically controlled valve attached to the injector body and including a control valve member movable between a first position in contact with a seat, and a second position out of contact with the seat; the needle control chamber being fluidly connected to the drain outlet by a third pathway that includes the A orifice, the intermediate chamber and an E orifice when the control valve member is at the second position, but the needle control chamber being blocked from the drain outlet when the control valve member is at the first position; the seat is fluidly positioned between the E orifice and the drain outlet: and a needle valve member with an opening hydraulic surface exposed to fluid pressure in the nozzle chamber, and a closing hydraulic surface exposed to fluid pressure in the needle control chamber.