A fuel injection system of an internal combustion engine includes: an injector having a hydraulic control chamber controlling the delivery of fuel through the injector, an actively controlled first valve system controlling the pressure relief from the control chamber, movable between: a first position in which the first valve system closes the injector by deterring the pressure from being relieved from the control chamber through the first relief circuit, and a second position in which the first valve system opens the injector by allowing the pressure to be relieved from the control chamber through the first relief circuit. A second relief circuit allows the pressure to be relieved from the control chamber through the second relief circuit. The second relief circuit includes a second valve system passively controlled by the fuel pressure and movable between two positions deterring or allowing the pressure to be relieved from the control chamber through the second relief circuit.

A fuel injection device includes a valve mechanism and a drive unit. The valve mechanism includes a first control valve body driven by a drive unit to open and close an outflow opening portion, a hydraulically actuated valve body for opening and closing an inflow opening portion by a pressure difference, and a second control valve body driven by the drive unit through the first control valve body. When a first drive energy is input to the drive unit, the second control valve body maintains a seated state on the hydraulically actuated valve body. When the second drive energy is input to the drive unit, the second control valve body is unseated from the hydraulically actuated valve body. According to the seating and unseating of the second control valve body, a flow channel area of a communication passage for communicating an upper control chamber portion with a lower control chamber portion is switched to another.

A fuel injector for an internal combustion engine is disclosed. The fuel injector is particularly suitable for use as a dual fuel injector, and comprises a generally tubular outer valve needle, an inner valve needle slidably received in the outer valve needle, and a nozzle body assembly comprising a tip part and a needle guide part. The tip part defines a seating region for the outer valve needle, and the needle guide part comprises a guide bore for slidably receiving the outer valve needle. In one embodiment, a lower bore region of the needle guide part defines a. cavity around the outer valve needle which houses a biasing spring for the outer valve needle and a fuel. A collar for seating the biasing spring can be dimensioned to allow free flow of the fuel from the cavity into an annular accumulator volume defined between the outer valve needle and the bore of the tip part.

A fuel injector (100) for an internal combustion engine is disclosed. The fuel injector is particularly suitable for use as a dual fuel injector, and comprises a generally tubular outer valve needle (130), an inner valve needle (140) slidably received in the outer valve needle (130), and a nozzle body assembly (112) comprising a tip part (120) and a needle guide part (118). The tip part (120) defines a seating region (120f) for the outer valve needle (130), and the needle guide part (118) comprises a guide bore (118e) for slidably receiving the outer valve needle (130). In one embodiment, the tip part (120) and the needle guide part (118) are made from different materials, and a biasing spring (148) for the outer valve needle (130) is housed in the nozzle body assembly (112).

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.

A nozzle for a member of a fuel combustion system of an engine includes a hollow nozzle body. The nozzle body includes an outer surface, an inner surface, and an orifice surface. The outer surface defines an outer opening. The inner surface defines an interior chamber and an inner opening. The orifice surface defines an orifice passage extending between, and in communication with, the outer opening and the inner opening. The orifice passage is in communication with the interior chamber via the inner opening. The orifice surface includes a boundary surface and a protrusion. The protrusion projects from the boundary surface radially inwardly into the orifice passage.