The fuel injection valve has a hydraulic control device for controlling the axial movement of the injection valve member. The stem of the intermediate valve member of mushroom-shaped configuration of the intermediate valve is guided in the guide recess of the intermediate part. In the open position, the intermediate valve member opens up a second connection between a high-pressure fuel inlet and a valve chamber and, in the closed position, the intermediate valve member shuts off the second connection between the high-pressure fuel inlet and the valve chamber. In the closed position of the intermediate valve member, the head of the intermediate valve member lies with a side facing toward the intermediate part against the intermediate valve seat via a first sealing surface, which runs around the stem or the guide recess at a first radial spacing so as to form a first annular sealing surface which is continuous in the circumferential direction.

An injector apparatus (210) for injecting fluid under pressure into an associated chamber (232) is provided. The injector apparatus (210) includes a first piston (214) defining a first working area facing an associated chamber, and a high pressure piston (218) defining a high pressure working area facing a high pressure chamber. The first working area is greater than the high pressure working area and the first piston is moveable in a body of the injector apparatus (210) to compress fluid in the high pressure chamber using the high pressure piston. The injector apparatus (210) further includes an accumulator (270) operable to supply fluid under pressure through an injector orifice (276) into an associated chamber (232), the high pressure chamber being operable to pressurise the accumulator (270) with fluid.

An engine head assembly includes a double-walled fuel connector assembly in an engine head and forming a high-pressure fuel supply passage and a low-pressure fuel return passage. The engine head assembly also includes a fuel injector. A high-pressure fuel inlet path extends between a fuel inlet and spray orifices through an injector body in the fuel injector. A low-pressure cooling fuel outlet path extends between an injection control valve seat in the fuel injector and a cooling fuel outlet in a nozzle case of the fuel injector. Expelled cooling fuel is passed through the low-pressure fuel return passage in the double-walled fuel connector.

The invention relates to a fuel injector for injecting fuel under high pressure, comprising a housing (1) equipped with a nozzle needle (10) which can be moved in a longitudinal direction and a seal surface (11) of which opens and closes one or more injection openings (13), fuel being injectable via said injection openings. A control chamber (20) which can be filled with fuel exerts a hydraulic pressure onto the nozzle needle (10) in the closing direction thereof, wherein the pressure in the control chamber (20) can be influenced by a control valve (22) in that the control valve (22) opens and closes a hydraulic connection between the control chamber (20) and a low-pressure chamber (21). The control valve (22) comprises a solenoid armature (23) which interacts with a control valve seat (26) in order to open and close the hydraulic connection, said solenoid armature (23) being radially guided in the housing (1) on the exterior (33) of the solenoid armature.

A variable orifice fuel injector has an inward opening needle valve and an outward opening needle valve and has means to directly inject two types of fuels independently and collectively. Both needle valves are fully contained in a nozzle body, with a co-axial smaller needle valve at least partially being contained in a larger needle valve. The materials of the needle valves are individually chosen such that it provides good sealings for liquid and gas fuels.

A first tubular portion forms a part of a fuel flow passage therein. A first joint surface is formed in one end surface of the first tubular portion. A first inner diameter enlarged portion is formed on a side opposite to the first joint surface. A second tubular portion forms a part of the fuel flow passage therein. A second joint surface is formed in one end surface of the second tubular portion and joined to the first joint surface. A second inner diameter enlarged portion is formed on a side opposite to the second joint surface. A welded portion is formed in an annular shape to extend radially inward from the radially outside of the first joint surface and the second joint surface by welding the first tubular portion and the second tubular portion.

A fuel injector includes an injector body and a valve stack within the injector body that includes a valve seat plate. The valve seat plate includes a pressure control passage for controlling fuel injection, and a valve seat positioned fluidly between the pressure control passage and a low-pressure drain. The valve seat plate includes a pressure-limiting annular groove that extends circumferentially around the valve seat and axially inward from a side of the valve seat plate where the valve seat is located. The groove enables deformation in response to pressure differences across the valve seat plate in a manner that limits stress concentrations.

A control valve assembly of a fuel injector includes a first valve arrangement wherein a first valve spool is guided in a first hydraulic bore provided in a body of the assembly. The control assembly further includes a first tubular sleeve having a seating portion which end face defines the first seating face, the first sleeve being fixed in the first hydraulic bore and the first spool extending through the sleeve.

A flow control system for a fuel injector of an internal combustion engine includes: an inlet channel, an outlet channel, a return channel for returning pressurized fuel to a low-pressure system having a lower pressure than the inlet channel, a fuel outlet chamber, a moveable nozzle control member in the fuel outlet chamber for selectively allowing the pressurized fuel to flow into the outlet channel, a biasing member biasing the nozzle control member towards a closed position, a moveable member defining, with the nozzle control member, a fuel control chamber configured to bias the nozzle control member towards its closed position, a moveable valve member for selectively opening and closing a flow passage and a fuel connection between the inlet channel and the fuel control chamber for pressurizing the fuel control chamber.

A fuel injector having a seat plate with a passage throttle; a valve insert arranged at a first side of the seat plate; a valve guide surrounding the valve insert and adapted for slidable reception of the valve insert; a spring sheath surrounding at least a section of a jet needle arranged at a second side of the valve insert, the second side opposite the first side and the seat plate; a valve chamber fluidly connected to the passage throttle; a control chamber adapted for reception of fuel; and a line arranged in the valve insert connecting the control chamber and the valve chamber to one another, wherein the line is closeable by placement of the valve insert onto the spring sheath.