Disclosed is an air-assisted fuel injection system, comprising a cylindrical bore; a plunger and a barrel within the cylindrical bore, the plunger having a flat surface; and a securing means abutting against the flat surface to keep the plunger from rotating within the cylindrical bore.

Systems and methods are provided for a direct-injection engine having at least one cylinder head comprising at least one cylinder, in which each cylinder is assigned an injection nozzle which: is at least connectable to a fuel reservoir which serves for storing fuel, is secured in a nozzle holder, and is fitted with a nozzle needle which is displaceable in the direction of a longitudinal axis in a nozzle needle guide and, opens up at least one nozzle hole in order to introduce fuel. A control piston may be mounted movably on the injection nozzle, is displaceable in a translatory manner along the longitudinal axis of the injection nozzle between an inoperative position and a working position, and closes at least one fluid connection in the inoperative position and opens up same in the working position in order to introduce water into the associated cylinder.

A pressure relief device for a gaseous fuel including a cylinder having a fuel inlet in a wall, an outlet at an open first end and an end wall at a closed opposing second end; a piston disposed within the cylinder, the piston having a first end adjacent the outlet of the cylinder defining an outlet orifice and a second opposing end slidably mounted within the cylinder between first and second end stops; and a spring mounted between the second end of the piston and the end wall of the cylinder, the spring arranged to bias the second end of the piston towards the second end stop, wherein movement of the piston along a longitudinal axis of the cylinder between the first and second end stops varies the outlet orifice to vary a flow of gaseous fuel between the fuel inlet and the outlet orifice.

A pressure relief device for a gaseous fuel including a cylinder having a fuel inlet in a wall, an outlet at an open first end and an end wall at a closed opposing second end; a piston disposed within the cylinder, the piston having a first end adjacent the outlet of the cylinder defining an outlet orifice and a second opposing end slidably mounted within the cylinder between first and second end stops; and a spring mounted between the second end of the piston and the end wall of the cylinder, the spring arranged to bias the second end of the piston towards the second end stop, wherein movement of the piston along a longitudinal axis of the cylinder between the first and second end stops varies the outlet orifice to vary a flow of gaseous fuel between the fuel inlet and the outlet orifice.