A fuel injector nozzle has a housing defining a blind bore with at least one fuel injection spray orifice defined at a bottom portion of a spray tip and a guide passage defined at a top portion of the bore. An injection chamber of the bore is disposed between the orifice and the guide passage. A fuel injection passage intersects the guide passage. A needle check is slidably disposed in the blind bore for movement between a first position and a second position. In the first position, a seat portion of the check is disposed in the bore against the bottom portion of the tip while a guide portion of the check together with the guide passage define a first flow area restricting fluid flow therethrough. In the second position, the seat portion of the check is spaced from the bottom portion of the tip, and the guide portion and guide passage define a second flow area larger than the first flow area and less restrictive of flow therepast.
The present invention relates to fuel injectors having the ability to inject fuel at multiple pressures during an injection event. Traditional fuel injectors used in common rail fuel injection systems and unit pump fuel injection systems typically did not have the ability to inject fuel at multiple pressures during an injection event. However, engineers have learned that increased control over an injection event can lead to improved emissions by the fuel injectors. Therefore, the present invention utilizes an electronically controlled valve member that can direct. the flow of fuel through a fuel injector during an injection event between a relatively restricted passageway and a relatively unrestricted passageway. The present invention finds particular application in both common rail fuel injection systems and electronic unit pump fuel injection systems used in diesel engines.
