Patent ID: 6616070
Filing Date: 2003-09-09
Classification: F02M

Abstract:
A fuel injector comprising a nozzle body having a blind bore defining first and second seatings therein, an outer valve needle slidable within the blind bore between at least a first seated position and a second open position, the outer valve needle provided with a bore, an inner valve needle slideable within the outer valve needle bore, the outer and inner valve needles being selectively engageable with the first and second seatings respectively to control the supply of fuel from the fuel injector the inner valve needle having a passage formed therein communicating with a sac chamber defined by the inner valve needle and the nozzle body and located downstream of the second seating, the outer valve needle cutting off fuel flow through the passage into the sac chamber when in the first seated position and permitting pressurized fuel to flow through the passage into the sac chamber primarily exposing one end but not an opposite end of the inner valve needle to the pressurized fuel when the outer valve needle is in the second open position, and the inner valve needle being slidably responsive in the outer valve needle bore to lift away from the second seating in response to fuel pressure within the sac chamber.