A fuel system for an internal combustion engine includes a pressurized fuel supply, and a fuel injector fluidly connected to the pressurized fuel supply. The fuel injector includes a valve seat plate forming a valve seat, an injection control valve, and a nozzle cavity. A filter, which can include a 2-dimensional filter, is positioned partially within the valve seat plate and partially within an injector body to filter an incoming flow of high-pressure fuel. The valve seat plate and filter are integrated in a valve seat plate and filter assembly.

A needle includes a first seal portion, which is formed at an end portion of the needle located on a side where an injection hole is placed, and a second seal portion, which is formed on a side of the first seal portion where a stationary core is placed. When a boundary between a first outer wall of the first seal portion and a second outer wall of the second seal portion is lifted away from or is seated against an inner wall, the injection hole is opened or closed. Thereby, a seat diameter of the boundary and the inner wall is stabilized, and a change in a fuel injection quantity caused by aging can be reduced. Furthermore, the first outer wall of the first seal portion is shaped into a form of a spherical surface.

A valve assembly for a fluid injector for an internal combustion engine includes a valve body with a valve recess, a central longitudinal axis, and a first axial end and a second axial end with respect to the central longitudinal axis. A valve needle is axially moveable within the valve recess with respect to the central longitudinal axis. In concurrence with a seal seat area the valve needle prevents a fluid flow through at least one flow hole in its closing position and otherwise enables it. Furthermore, the injector comprises a sac volume step adjacent to the seal seat area forming a part of an inner surface of a wall of the valve body and a sac volume being designed as one end of the valve recess and being limited by a further part of the inner surface of the wall of the valve body.

A fuel injector is provided that includes various precise configuration parameters, including dimensions, shape and/or relative positioning of fuel injector features, resulting in improved efficiency of fuel flow through the fuel injector.

A fuel injector is provided that includes various precise configuration parameters, including dimensions, shape and/or relative positioning of fuel injector features, resulting in improved efficiency of fuel flow through the fuel injector.

A fuel injector may include a housing, a pintle nozzle assembly and an actuation assembly. The housing may define a longitudinal bore, a high pressure fuel duct in communication with the longitudinal bore and a valve seat including a valve seat surface and an aperture. The pintle nozzle assembly may include a stem and a pintle and may be at least partially disposed within the longitudinal bore and be variably displaceable between a first position and a second position. In the first position, the pintle nozzle assembly may abut the valve seat to seal the aperture. In the second position, the pintle nozzle assembly may be displaced from the valve seat to open the aperture. The actuation assembly may be coupled with the pintle nozzle assembly and operate to move the pintle nozzle assembly to a plurality of positions between the first position and the second position.

In a nozzle, in a cross section including an axis of a nozzle body, a side surface and a seat surface are both smoothly connected to an arc of a circle inscribing both the side surface and the seat surface. A part of a needle which is adjacent to a tip end side of a seat portion is a cone having a diameter reduced toward a tip end side of the cone in the axial direction. Thus, no corner is on the seat surface or the side surface, and the two surfaces form one curved surface. Since a cavitation generated in a sack chamber can be reduced, even when an injection quantity is significantly small such that an injection port does not throttle an injection flow, a flow coefficient of the injection flow is improved and a penetration of a spray of the fuel can be maintained.

A nozzle body for a fluid injection includes a cavity and a bottom wall delimiting the cavity at a fluid outlet end. The bottom wall is perforated by an injection hole having an inlet opening at an inner surface of the bottom wall and an outlet opening at an outer surface of the bottom wall. The outlet opening has an elongated slit shape having a centerline which is a circular arc with respect to the longitudinal axis. The inlet opening is spaced apart from the longitudinal axis by a radial distance. The inner surface has a concave shape extending away from the fluid outlet end from an apex of the inner surface. Further, the inlet opening is spaced apart from the apex by an axial distance that is smaller than said radial distance.