Patent ID: 6953157

Claim:
In a fuel injection system for an internal combustion engine, having one high-pressure fuel pump ( 10 ) and one fuel injection valve ( 12 ), communicating with it, for each cylinder of the engine, wherein the high-pressure fuel pump ( 10 ) has a pump piston ( 18 ), which is driven by the engine in a reciprocating motion and defines a pump work chamber ( 22 ) to which fuel is delivered from a fuel tank ( 24 ), wherein the fuel injection valve ( 12 ) has a pressure chamber ( 40 ), communicating with the pump work chamber ( 22 ), and an injection valve member ( 28 ), by which at least one injection opening ( 32 ) is controlled and which is urged by the pressure prevailing in the pressure chamber ( 40 ) counter to a closing force in the opening direction ( 29 ) to open the at least one injection opening ( 32 ), having a first control valve ( 78 ), by which a connection ( 76 ) of the pump work chamber ( 22 ) with a relief chamber ( 24 ) is controlled, and having a second control valve ( 80 ), by which a connection ( 74 ) of a control pressure chamber ( 62 ) of the fuel injection valve with a relief chamber ( 24 ) is controlled, wherein the control pressure chamber ( 62 ) at least indirectly has a connection ( 62 ) with the pump work chamber ( 22 ), in which connection a first throttle restriction ( 73 ) is provided, and the control pressure chamber ( 62 ) is defined by a control piston ( 60 ), which acts on the injection valve member ( 28 ) in a closing direction, the improvement comprising a second throttle restriction ( 75 ) with a fixed flow cross section in the connection ( 74 ) of the control pressure chamber ( 62 ) with the relief chamber ( 24 ), wherein the control piston ( 60 ), with its side ( 66 ) remote from the injection valve member ( 28 ), controls a flow cross section from the control pressure chamber ( 62 ) to the connection ( 74 ) with the relief chamber ( 24 ) as a function of the stroke of the control piston ( 60 ); wherein with an increasing opening stroke of the injection valve member ( 28 ) providing a smaller flow cross section uncovered by the control piston ( 60 ); and wherein at a maximum opening stroke of the injection valve member ( 28 ), the uncovered flow cross section is less than the flow cross section of the second throttle restriction ( 75 ).