Fuel injection valve with stepped injection

Abstract

A fuel injection valve for internal combustion engines, especially for Diesel engines, which is equipped with a valve needle acted upon in the closing direction by a spring and in the opening direction by the pressure of the fed fuel, to which is coordinated a pressure space formed together with the valve housing and adapted to be closed off against the outside by the valve seat of the valve needle; at least one discharge opening is arranged downstream of the valve seat as viewed in the flow direction which represents a predetermined throttle resistance; the injection valve is additionally equipped with at least two pistons kinematically coupled with one another in one direction of movement whereby a pressure space is formed on each side of the pistons; the pistons, on the inlet side, are adapted to be acted upon at least indirectly by the pressure of the fed fuel and, on the outlet side, at least indirectly by a return spring; an unobstructed connection exists between the outlet side piston pressure space of at least one of the pistons with the pressure space of the valve needle while an unobstructed line connection exists from the space defined by a control edge and the pressure space of the valve needle; the outlet side pressure space of the main injection piston is connected with a reservoir by way of a line having a predetermined throttling effect.