Patent ID: 8690075

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, an intermediate chamber and a buffer 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 valve seat, and a second position out of contact with the valve seat; the needle control chamber being fluidly connected to the drain outlet by a third pathway that includes the A orifice, the intermediate chamber, an E orifice and the buffer chamber 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; 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.